300cc tuning and performance - Page 3

spldart · 01-12-2018, 09:18 PM

Pictures of motor mods please so we can all drool and get the fizzies!

kilo0195 · 01-21-2018, 07:36 PM

[IMG]https://ibb.co/fR6G3b
https://ibb.co/kk7TGw
https://ibb.co/cmM5ww
https://ibb.co/k12dGw
https://ibb.co/nNEsbw
https://ibb.co/dtnCbw
https://ibb.co/mtiUOb
https://ibb.co/jzNZpG[/IMG]

kilo0195 · 01-21-2018, 08:20 PM

Ok finally got the pics to upload properly... or links anyways. The first pic is the bike itself. There's a pic of my filter setup that I've talked about elsewhere. Just took my k&n out of the box, tossed the box, and epoxied the rubber tube from the carb to the outside of the filter. The zip ties held it in place to dry and I left them for extra strength. There's also a comparison of the 2 different jugs with the original piston and jug on top. Sorry about the crappy photos of the port jobs. Removed all casting marks originally. I went back today and smoothed the intake tube transitions and flattened the curves. The exhaust I rounded the curves as much as possible and opened the the ends to match the new pipes as the old ones had a sort of ramp inside of them that made the inside pipe diameters as the head about 1/2". Now they're about an 1" inside. The head I touched today as well, I trenched the squish areas (as they're dramatically bigger now with a 6mm larger piston) angling them towards the plug and gradually getting deeper and wider towards the chamber. The head was also domed, meaning that the ridges between the combustion chamber and valves, plug, etc were removed and rounded. The areas were left rough to promote better turbulence on intake and compression. There's a pic also of the piston still in the bottom as well as a pic of the new cam about to go in. The jug will be decked another .045 this week before I start putting it back together. As far as how she's been running since the original work.... rich... which is an understatement. I had a lot of carbon to remove from the Head and piston. The the gasket was in great shape, as well as the cylinder wall, rings, piston, rod, and pin. Nothing out of the ordinary when I inspected everything closely. All in all definitely recommend the 300cc swap from China. For $130 I think it was and about 5 hours of time it's a pretty cheap and easy mod if you're mechanically inclined. The other work isn't necessary but doesn't take long and can be done yourself as well... minus the decking unless you have a mill. The cam is the most expensive part and will run you I think they said about $200. You can get titanium springs and retainers for a 95 dr250 for another $200 online If you're inclined. While not required for the cam profile it's added insurance for me with the way I push it. If you do the exhaust openings it will probably cost you a bit to have new pipes made if you can't make those yourself. All in all I paid more for the used and neglected bike than I did for all of the additions combined.
The new shocks, drag bars, sissy bar and brackets, engine mods, sprockets, chain, paint lights... pretty much everything and the bike itself is in the $2,000 to $2200 area. The rich issue is from the starter jet... It's currently a 60 and reguardless of what one may think it effects fuel delivery throughout the rpm range even without choke... and no I don't have choke issues I checked. I'll be dropping that back to a 52.5, changing the pilot from a 17.5 to 20, and main from 147.5 to 150 while taking a couple shims out of the needle. I know that the stock pilot, starter, and a 147.5 main it will run very very lean. The different jets will hopefully correct everything or at least get me in the ballpark. I'll start there and go where it needs from there. When i can afford it I'll dyno tune and run it to get the final numbers.

kilo0195 · 01-22-2018, 05:45 PM

I think I found my oil consumption problem. Part of it I suspect being riding so hard at high rpm's. The other part of it I found is that my breather filter is soaked. It's not dripping, but completely soaked. This tells me that plenty of oil is getting to it and more than likely coming out when I'm in the high rpm's. My theory is that the larger piston is causing extra pressure in the crankcase on the downstroke. This would naturally force more oil into the breather. Right now the breather is attached to the end of the short stock vent hose. I'm going to extend it and mount the breather right under the seat next to the air filter. Hopefully the extra length and elevation will solve it. Otherwise I will have to find other and probably more expensive and extensive solutions. I wonder if a small oil cooler would help eliminate some pressure? A line from the pressure check port to cooler and then to a tap put in the oil filter cover? I'm sure the bike would be thanking me dearly for one anyways with the extra stress on the current setup.

Water Warrior 2 · 01-22-2018, 07:34 PM

Good pics and write-up. Your thread is very educational for any members who are after more performance but don't want a bigger bike. Looking to more updates.

kilo0195 · 01-22-2018, 08:25 PM

That's ultimately what I wanted to achieve... was a cheap bike that could be made to handle more on the cheap. Around here you can pick these bikes up for $1000 and they can modified pretty cheap. I wanted to try and accomplish what others said was impossible for this bike, and show that it can be done for little money. With the 300cc kit itself I was able to easily run a 16t front and 39t rear sprocket and have plenty of torque for 70-75mph and could easily hit 80-82mph for passing. It could peg the needle at 88 but was a little slower climb past 80. This makes the bike very capable for highway speeds and reliability at those speeds. The other mods are probably more than most people's cup of tea but turns the bike into something that can easily keep pace with most 650 and 750cc cruisers. The cam I'm hoping will bring some more torque to the mid and top end to help with passing especially if I have an extra 100lbs or so of rider on the back. The sprockets I'll keep the same as 4th gear now is basically what the stock 5th gear used to be. It allows me to use 5th as basically an overdrive for the highway. The bike is most alive in 3rd and 4th and in those gears feels like I've got twice the motor under me. If anybody has questions I'm more than happy to answer or help if they're interested in building theirs up. The big thing to note for internal parts wise is that the 91-95 Suzuki dr250 is essentially the same size for many parts. The heads are different, the dr250 has more oil journals than the gz that won't match up to your jug. Otherwise it would be nice because half the porting work is already done. Inside the Head though all the rockers, springs, retainers, bearing washer etc etc are same size specs. For these parts there are plenty of aftermarket beefier items you can buy. Unfortunately the bottom end is completely different. The bottom end internals seem to be holding up fine so I don't think anyone needs to worry about rods and the like. That's also with me pushing the bike harder than the average person would. So if 300cc is all someone is wanting to do then I'd suggest that along with Kevlar clutch plates, 16t and 39t sprockets, and the obvious rejetting. One should be able to get all of that for under $300.

Water Warrior 2 · 01-23-2018, 11:58 PM

Quote:

Originally Posted by kilo0195

So if 300cc is all someone is wanting to do then I'd suggest that along with Kevlar clutch plates, 16t and 39t sprockets, and the obvious rejetting. One should be able to get all of that for under $300.

I would be willing to bet most riders would really like the extra 20% in displacement and just a 16 tooth sprocket to start. The extra CC's and slightly lower RPM might be very satisfying. The GZ would then have a bit more grunt on long slight uphill grades and into headwinds. My late wife Lynda had that as her only complaint on long trips. New clutch plates would be an obvious option if there was slippage of course.

I may be wrong but I think you are the only rider to actually upgrade a GZ to this level. Your project is fantastic.

kilo0195 · 01-24-2018, 06:26 PM

The 300cc gave me enough torque with a 16t to pass uphill while I was cruising about 70mph... I'm about 155lbs.

The oil cooler issue I found on alliexpress as well. $79 gets you a kit for a gn250 that includes everything you need. One hose goes into the oil pressure check port and the other goes into a ported oil filter cover that's included. I ordered that one for the insurance and peace of mind. I haven't been able to get good temps readings but I'm sure especially after the new setup I will be running a little warm. It says it will be up to 45 days to get here though... bummer. At least it's cold outside.

As far as upgrading to this level... I think I was outdone before I started. In my research before the 300cc I came across photos of a gz with a pulley attached to the crank on the stator side. They were using that to power an AMR300 roots type blower. I'm pretty sure it was making far more power than I will be haha. That said I'm confident I spent far less than they did. My NA route is probably a little more reliable as well.

Another thing I will try to do when I get my jug back tomorrow is calculate my compression ration. I shaved the Head a little already but I also countered that probably when I domed the combustion chamber. I basically removed all the sharp ridges and made everything a nice round dome instead of its stock lumpy dome form. They're taking .050 off the jug which on average would bump CR by a full point. Keep in mind though there is also now an extra 3mm wide squish area all the way around the combustion chamber on the head. If I had to guess I'd say it will probably be close to 10.5/1

kilo0195 · 01-24-2018, 09:48 PM

Was able to get everything today to calculate my CR. Comes out to 10.42/1 roughly. To get my chamber volume I used water with dish soap (to reduce surface tension), put spark plug in, then put a flat and clear film over the chamber. I then put a small hole in the film so that I could add the water. This ensures the water is level and also reduces the circumference at which the water will want to try and raise above the surface of the film. Can't remember the names from chemistry or whatever but hopefully you get what I'm trying to say. After carefully measuring I was able to get the same numbers back to back so I called it good enough. Also looks like I'll need a single indexing washer for the plug to ensure it's facing the right way. Seems as I can only get the washers in a package for about $14 I think I will spend the $20 and just get a Brisk 360 degree plug. Then I will cut the spark plug port down inside the chamber to match the plug evenly all the way around. Yes I'm getting a bit anal with the details but it's all apart and I might as well take the extra few minutes and do what I can to better flame propagation. It also doesn't cost me a thing. Even if it doesn't remotely increase power to some millionth degree it will still help eliminate detonation problems from hot spots next to the plug. Anyways back to the CR point. If one was to buy a 300cc kit and also have the jug shaved .050... you'd have a CR somewhere around 10.4 to 10.5 fyi.

kilo0195 · 01-27-2018, 03:32 AM

I got it all back together today. I couldn't remove my stator cap to access the crank, so I had to turn it by pulling the timing chain to line the cam and gear up. I must say that this part alone took me about an hour all because I couldn't get a wrench on the crank to keep it from moving. I stripped the slotted part of the cap in my attempt to free it so I'm not sure how I'm getting it out in the future. Anyways other than that it was smooth sailing. My starter got a work out as it took a little effort to get it to turn over. I might increase the size of the wire to see if easier juice flow helps. Filled the tank with 93 to start, but will try 89 octane down the road to see if it still can run without detonation. My jets still haven't came in so the carb is still the same. Like I said before it was way rich low and was ideal high rpm and full throttle. Now it feels right down low and up until about half throttle. Full throttle and it feels lean with it barely dropping out of power occasionally. It was passable to get the cam broke in though. First impressions? Keep in mind the carb jetting is off... There's torque a plenty down low. A good bit of this will probably be from the 1.4 point CR increase. Up until about 4500-5000 rpm the torque difference feels kind of like when I changed to the 300cc from the 250. Up top she struggles a bit, but that would be from fuel delivery I'm almost positive. The cam grind should increase power throughout the rpm range with a focus on the mid to top end, so it should be night and day difference when it's jetted properly. I'm hoping when all is tuned properly that I can run the dyno close to the 30whp mark.

Side note I shielded my plug wire and coil and still have tons of interference in the tach signal. I have just no clue at this point other than maybe the generator causing a large magnetic field.

01-12-2018, 09:18 PM	#21
spldart Senior Member Join Date: May 2015 Location: Stafford, Texas Posts: 604	Pictures of motor mods please so we can all drool and get the fizzies! Login or Register to Remove Ads
	0

01-21-2018, 08:20 PM	#23
kilo0195 Member Join Date: Jul 2017 Location: Illinois Posts: 52	Ok finally got the pics to upload properly... or links anyways. The first pic is the bike itself. There's a pic of my filter setup that I've talked about elsewhere. Just took my k&n out of the box, tossed the box, and epoxied the rubber tube from the carb to the outside of the filter. The zip ties held it in place to dry and I left them for extra strength. There's also a comparison of the 2 different jugs with the original piston and jug on top. Sorry about the crappy photos of the port jobs. Removed all casting marks originally. I went back today and smoothed the intake tube transitions and flattened the curves. The exhaust I rounded the curves as much as possible and opened the the ends to match the new pipes as the old ones had a sort of ramp inside of them that made the inside pipe diameters as the head about 1/2". Now they're about an 1" inside. The head I touched today as well, I trenched the squish areas (as they're dramatically bigger now with a 6mm larger piston) angling them towards the plug and gradually getting deeper and wider towards the chamber. The head was also domed, meaning that the ridges between the combustion chamber and valves, plug, etc were removed and rounded. The areas were left rough to promote better turbulence on intake and compression. There's a pic also of the piston still in the bottom as well as a pic of the new cam about to go in. The jug will be decked another .045 this week before I start putting it back together. As far as how she's been running since the original work.... rich... which is an understatement. I had a lot of carbon to remove from the Head and piston. The the gasket was in great shape, as well as the cylinder wall, rings, piston, rod, and pin. Nothing out of the ordinary when I inspected everything closely. All in all definitely recommend the 300cc swap from China. For $130 I think it was and about 5 hours of time it's a pretty cheap and easy mod if you're mechanically inclined. The other work isn't necessary but doesn't take long and can be done yourself as well... minus the decking unless you have a mill. The cam is the most expensive part and will run you I think they said about $200. You can get titanium springs and retainers for a 95 dr250 for another $200 online If you're inclined. While not required for the cam profile it's added insurance for me with the way I push it. If you do the exhaust openings it will probably cost you a bit to have new pipes made if you can't make those yourself. All in all I paid more for the used and neglected bike than I did for all of the additions combined. The new shocks, drag bars, sissy bar and brackets, engine mods, sprockets, chain, paint lights... pretty much everything and the bike itself is in the $2,000 to $2200 area. The rich issue is from the starter jet... It's currently a 60 and reguardless of what one may think it effects fuel delivery throughout the rpm range even without choke... and no I don't have choke issues I checked. I'll be dropping that back to a 52.5, changing the pilot from a 17.5 to 20, and main from 147.5 to 150 while taking a couple shims out of the needle. I know that the stock pilot, starter, and a 147.5 main it will run very very lean. The different jets will hopefully correct everything or at least get me in the ballpark. I'll start there and go where it needs from there. When i can afford it I'll dyno tune and run it to get the final numbers. Login or Register to Remove Ads
	1

01-22-2018, 07:34 PM	#25
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	Good pics and write-up. Your thread is very educational for any members who are after more performance but don't want a bigger bike. Looking to more updates. Login or Register to Remove Ads
	2

01-21-2018, 07:36 PM	#22
kilo0195 Member Join Date: Jul 2017 Location: Illinois Posts: 52	[IMG]https://ibb.co/fR6G3b https://ibb.co/kk7TGw https://ibb.co/cmM5ww https://ibb.co/k12dGw https://ibb.co/nNEsbw https://ibb.co/dtnCbw https://ibb.co/mtiUOb https://ibb.co/jzNZpG[/IMG]
	1

01-22-2018, 05:45 PM	#24
kilo0195 Member Join Date: Jul 2017 Location: Illinois Posts: 52	I think I found my oil consumption problem. Part of it I suspect being riding so hard at high rpm's. The other part of it I found is that my breather filter is soaked. It's not dripping, but completely soaked. This tells me that plenty of oil is getting to it and more than likely coming out when I'm in the high rpm's. My theory is that the larger piston is causing extra pressure in the crankcase on the downstroke. This would naturally force more oil into the breather. Right now the breather is attached to the end of the short stock vent hose. I'm going to extend it and mount the breather right under the seat next to the air filter. Hopefully the extra length and elevation will solve it. Otherwise I will have to find other and probably more expensive and extensive solutions. I wonder if a small oil cooler would help eliminate some pressure? A line from the pressure check port to cooler and then to a tap put in the oil filter cover? I'm sure the bike would be thanking me dearly for one anyways with the extra stress on the current setup.
	0

01-22-2018, 08:25 PM	#26
kilo0195 Member Join Date: Jul 2017 Location: Illinois Posts: 52	That's ultimately what I wanted to achieve... was a cheap bike that could be made to handle more on the cheap. Around here you can pick these bikes up for $1000 and they can modified pretty cheap. I wanted to try and accomplish what others said was impossible for this bike, and show that it can be done for little money. With the 300cc kit itself I was able to easily run a 16t front and 39t rear sprocket and have plenty of torque for 70-75mph and could easily hit 80-82mph for passing. It could peg the needle at 88 but was a little slower climb past 80. This makes the bike very capable for highway speeds and reliability at those speeds. The other mods are probably more than most people's cup of tea but turns the bike into something that can easily keep pace with most 650 and 750cc cruisers. The cam I'm hoping will bring some more torque to the mid and top end to help with passing especially if I have an extra 100lbs or so of rider on the back. The sprockets I'll keep the same as 4th gear now is basically what the stock 5th gear used to be. It allows me to use 5th as basically an overdrive for the highway. The bike is most alive in 3rd and 4th and in those gears feels like I've got twice the motor under me. If anybody has questions I'm more than happy to answer or help if they're interested in building theirs up. The big thing to note for internal parts wise is that the 91-95 Suzuki dr250 is essentially the same size for many parts. The heads are different, the dr250 has more oil journals than the gz that won't match up to your jug. Otherwise it would be nice because half the porting work is already done. Inside the Head though all the rockers, springs, retainers, bearing washer etc etc are same size specs. For these parts there are plenty of aftermarket beefier items you can buy. Unfortunately the bottom end is completely different. The bottom end internals seem to be holding up fine so I don't think anyone needs to worry about rods and the like. That's also with me pushing the bike harder than the average person would. So if 300cc is all someone is wanting to do then I'd suggest that along with Kevlar clutch plates, 16t and 39t sprockets, and the obvious rejetting. One should be able to get all of that for under $300.
	0

01-24-2018, 06:26 PM	#28
kilo0195 Member Join Date: Jul 2017 Location: Illinois Posts: 52	The 300cc gave me enough torque with a 16t to pass uphill while I was cruising about 70mph... I'm about 155lbs. The oil cooler issue I found on alliexpress as well. $79 gets you a kit for a gn250 that includes everything you need. One hose goes into the oil pressure check port and the other goes into a ported oil filter cover that's included. I ordered that one for the insurance and peace of mind. I haven't been able to get good temps readings but I'm sure especially after the new setup I will be running a little warm. It says it will be up to 45 days to get here though... bummer. At least it's cold outside. As far as upgrading to this level... I think I was outdone before I started. In my research before the 300cc I came across photos of a gz with a pulley attached to the crank on the stator side. They were using that to power an AMR300 roots type blower. I'm pretty sure it was making far more power than I will be haha. That said I'm confident I spent far less than they did. My NA route is probably a little more reliable as well. Another thing I will try to do when I get my jug back tomorrow is calculate my compression ration. I shaved the Head a little already but I also countered that probably when I domed the combustion chamber. I basically removed all the sharp ridges and made everything a nice round dome instead of its stock lumpy dome form. They're taking .050 off the jug which on average would bump CR by a full point. Keep in mind though there is also now an extra 3mm wide squish area all the way around the combustion chamber on the head. If I had to guess I'd say it will probably be close to 10.5/1
	0

01-24-2018, 09:48 PM	#29
kilo0195 Member Join Date: Jul 2017 Location: Illinois Posts: 52	Was able to get everything today to calculate my CR. Comes out to 10.42/1 roughly. To get my chamber volume I used water with dish soap (to reduce surface tension), put spark plug in, then put a flat and clear film over the chamber. I then put a small hole in the film so that I could add the water. This ensures the water is level and also reduces the circumference at which the water will want to try and raise above the surface of the film. Can't remember the names from chemistry or whatever but hopefully you get what I'm trying to say. After carefully measuring I was able to get the same numbers back to back so I called it good enough. Also looks like I'll need a single indexing washer for the plug to ensure it's facing the right way. Seems as I can only get the washers in a package for about $14 I think I will spend the $20 and just get a Brisk 360 degree plug. Then I will cut the spark plug port down inside the chamber to match the plug evenly all the way around. Yes I'm getting a bit anal with the details but it's all apart and I might as well take the extra few minutes and do what I can to better flame propagation. It also doesn't cost me a thing. Even if it doesn't remotely increase power to some millionth degree it will still help eliminate detonation problems from hot spots next to the plug. Anyways back to the CR point. If one was to buy a 300cc kit and also have the jug shaved .050... you'd have a CR somewhere around 10.4 to 10.5 fyi.
	1

01-27-2018, 03:32 AM	#30
kilo0195 Member Join Date: Jul 2017 Location: Illinois Posts: 52	I got it all back together today. I couldn't remove my stator cap to access the crank, so I had to turn it by pulling the timing chain to line the cam and gear up. I must say that this part alone took me about an hour all because I couldn't get a wrench on the crank to keep it from moving. I stripped the slotted part of the cap in my attempt to free it so I'm not sure how I'm getting it out in the future. Anyways other than that it was smooth sailing. My starter got a work out as it took a little effort to get it to turn over. I might increase the size of the wire to see if easier juice flow helps. Filled the tank with 93 to start, but will try 89 octane down the road to see if it still can run without detonation. My jets still haven't came in so the carb is still the same. Like I said before it was way rich low and was ideal high rpm and full throttle. Now it feels right down low and up until about half throttle. Full throttle and it feels lean with it barely dropping out of power occasionally. It was passable to get the cam broke in though. First impressions? Keep in mind the carb jetting is off... There's torque a plenty down low. A good bit of this will probably be from the 1.4 point CR increase. Up until about 4500-5000 rpm the torque difference feels kind of like when I changed to the 300cc from the 250. Up top she struggles a bit, but that would be from fuel delivery I'm almost positive. The cam grind should increase power throughout the rpm range with a focus on the mid to top end, so it should be night and day difference when it's jetted properly. I'm hoping when all is tuned properly that I can run the dyno close to the 30whp mark. Side note I shielded my plug wire and coil and still have tons of interference in the tach signal. I have just no clue at this point other than maybe the generator causing a large magnetic field.
	1