07-28-2017, 07:01 AM | #1 |
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Join Date: Jul 2017
Posts: 8
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Lacking power in 3/4/5 gear
New gz250 owner (2003 15k miles).. seemed to run great on a brief, back-road test drive.. Luckily it was cheap, and factored in some $ on maintenance, etc..
Honestly the bike seems to run great... it revs up well in neutral. In first gear the bike accelerates well and buzzes right upto ~25mph, and upto 35mph+ in 2nd gear... in 3rd/4th/5th, I can get the bike upto ~45 (barely maybe 50mph downhill)... in 4th and 5th the bike just won't speed up much at all. There are a few similar helpful posts..but nothing conclusive! I have gone through and read a lot, downloaded the service & owners manuals, and done searches on this forum & google, and I think I have covered most of the basics.. A couple quick notes: -previous owner had the oil about 1/4-1/2 quart overfilled. not sure type of oil or anything, or for how long, but oil didn't look bad when drained. -in neutral I can hear a slight ticking sound that is not there when in gear, seems like it's possibly from the clutch/ transmission area... not bad or obvious (not sure if this is normal) but noticeable -old spark plug maybe seemed a little whitish or dry.. So far I have -Emptied fuel tank, new fuel filter, checked petcock for good flow -Fresh gas with strong dose of seafoam. -Drained carb and filled with straight seafoam, then let sit overnight. The gas that drained out of the carb didn't seem visually bad, gelled or anything at all.. -Fresh motorcycle rated oil -New air filter -New plug -Adjusted clutch cable, set to dime gap, then tried going for extra slack/play before it engages to be sure. -Bike coasts well so it doesn't seem like any extra resistance anywhere. -Tested for air leaks around intake boots and rubber hoses by spraying starter fluid around those areas while running, no change in idle speed. Tank vent is working. I haven't yet pulled the carb for a clean/rebuild, or checked the valve clearances, or checked the compression yet. I have put about 50 miles on it after doing the things listed above and it hasn't changed much at all..so I don't think it really feels like a carb issue that is going to clear up with carb cleaner in the gas. I am hoping, at this point that a full carb cleaning will be all it needs! Really crossing my fingers because beyond that, I might be hiring a mechanic. If that doesn't do it, next I will try to figure out if adjusting/checking the valve clearances is something I can do myself. Finally, I wonder if anyone can describe or link me to any references for checking or evaluating if this might be an issue caused by the clutch? (clutch slippage) IS THERE ANYTHING I AM MISSING? thoughts, advice or encouragement greatly appreciated! thanks! Login or Register to Remove Ads Last edited by new_bee; 07-28-2017 at 07:05 AM. |
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07-28-2017, 11:38 AM | #2 |
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Join Date: Jan 2013
Location: Murcia, Spain
Posts: 683
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If the bike has a 16 tooth rear sprocket, you can expect some loss of power in 4th and 5th. Worth checking.
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"It begins here for me on this road. How the whole mess happened I don't know, but I know it couldn't happen again in a million years." (Johnny Strabbler-The Wild One 1953) |
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07-28-2017, 02:20 PM | #3 |
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Join Date: May 2015
Location: Henderson, NV
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I have a 16 tooth front sprocket and although it is not as peppy in 4th and 5th, I still have plenty of power to take it up to 70/75 mph on the flat with no head wind. I don't think that is a factor.
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07-29-2017, 01:03 AM | #4 |
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Join Date: Jul 2017
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Stock sprockets/gearing g.
Anything else I should check before I pull the carb as the next step? |
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07-31-2017, 12:50 AM | #6 |
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Join Date: Oct 2007
Location: HoCo, Maryland
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Good. To finish things off, I'd check the valve clearances.
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2005 "Saturn Black", stock + tach |
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08-22-2017, 11:02 PM | #7 |
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Join Date: Jul 2017
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So after around 20 miles of running, the problem was back. It seems like the same exact symptoms, lacking power, and the symptoms seems to have come on fairly quickly.
I believe the diaphragm might not be sealing correctly in the grove, I took it apart twice, the second time I put it back together with a small amount yamabond adhesive around the o ring, but still runs the same. I've ordered a new diaphragm but not sure if I should have ordered the whole diaphragm slide assembly. I checked the valve clearances and they are within special. But I noticed a minor oil leak behind the left top engine access cover. I wasn't really able to identify where it was coming from. Any thoughts on either issue appreciated |
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08-24-2017, 01:01 PM | #9 |
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Join Date: Jan 2017
Location: KS
Posts: 103
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Is there junk in the tank that is clogging a jet? I would clean the carb again and install an inline filter in the fuel line. A problem with the diaphragm sounds unlikely. It doesn't take very much at all to plug up a jet
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2003 Suzuki GZ250 (Sold) 1986 Suzuki Cavalcade LXE 1986 Suzuki Intruder VS700 |
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08-25-2017, 01:15 AM | #10 |
Junior Member
Join Date: Jul 2017
Posts: 8
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There's a new inline filter (old wasn't bad), and tank is clean.. No junk in carb at all both times I cleaned it.
Thanks for heads up on head bolts |
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