Gt250 almost no compression
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On topic sort of . Just did a compression check : Both cyl peak at 140 psi with throttle WFO and engine relatively warmed up. Before this, the engine was smoking from the exhaust . When I removed the spark plugs ,the the rear was black with soot while the front appeared normal. I assume the rear is running rich?Jetting issue?Carbs recently rebuilt . Both jets were the same in the kit,but if memory serves the factory calls for bigger on one vs. the other . I assume again it is for cooling? ( this bike was/is a basketcase owned I believe by Methhead gangsta mechanics.)It is a 2008 gt250r with 7300 miles on the odometer So my next step is to check the valve clearance then test. I really don’t want to pull the carbs again as the clamps have to be placed precisely to avoid interference with the carb linkages. I very well may just be an idiot(likely) Also,egr at rear cyl is capped off both intake nipples are tee’d to fuel pump.The small tee fitting has been eliminated between the carbs and the left side (bowl overflow?) is joined with no vent.
I think beyond confusion there may be a question or two above.
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EGR = Just make sure the actual engine cylinders are blanked there.
Then Front & Rear Rubber Intake pipes from the cylinder heads feed the Tank Tap and Fuel Pump
Check airbox has an extra hole for the EGR is blanked off.
Do the valve clearances and see how it behaves.
If you remove the carbs again and the intake pipes are wet inside, you may have a slow leak in to cylinders due to jammed floats or float seat assemblies needing a replacement, could be what is happening to the rear cylinder of the engine.
// Meditation doesn't mean you have to sit still....
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Today I found out it’s shim under bucket 🙁 never done those before. Is there a service manual on here for a 2008 gt250r? (Not sure where to look) Online I have only found partial manuals. I think you were correct on the stuck float thing . I pulled the air filter and there was a puddle of fuel towards the nose . Also, I did plug the egr hole in the airbox and I am going to run vac.from the front cyl boot to the pump directly and rear cyl to the diaphragm on the petcock directly instead of tees. Unless there is a balance issue?
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Those vacuum routing methods are good. Each cylinder has enough vacuum to run each tap and pump independently.
Check “ManualsLIB” website , they have the WorkShop Manual which has cartoon diagrams of how to do clearances. All Hyosung 250cc vtwins are the same (Carb & EFI until 2020) when it comes to valve adjustments.
Puddle in airbox = If its OIL (it could be blowby gasses mixed with oil during heat and finally condensed in to an oily liquid
If its fuel , it will be very obvious and smell strong of it and usually pure fuel will cut through the oil and turn the oil in to a water like substance , it may appear black or almost colourless. Check air filter. Again, i could guess as i can’t see what’s going on, so you should examine the texture of that liquid.
Some engine gasses are OK, but a flood like puddle in the airbox isn’t good. Either oil or fuel.
// Meditation doesn't mean you have to sit still....
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I ran the bike today with an aux tank , still hooked to pump. There is a steady stream of fuel coming out of the front carb where the red straw is in the photo while the bike is running. I pulled the float bowls the other day and confirmed that the fuel flow stopped when pushing the floats up. I have no idea what I am missing here or why I would have this much pressure to cause the stream. I’ll put a pic of the aux tank setup. Also I haven’t found the service manual yet to see procedures for checking the valve clearances. As far as just checking the clearance I don’t think it would much different than my old ninja 500,cam lobes in a neutral position and such. Also,if I am posting this in the wrong spot let me know.
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Strange , visit ManualsLIB website again and use GV250 or GV125 service manual yes the 125cc version uses the same clearances as its 250cc sister. The system used is “Suzuki Cam Under Bucket” (Shims in a Tappet)” , so its definitely advised to use the service manual.
If fuel is coming out of that straw, you have jammed float seats (so replace the entire float pin and float seat even, since the float pin has a spring inside) , then use make sure floats are 7mm height and it will raise up to about 13-17mm when the bike is running
However, look at my reply in this topic
if it is adamant the float system is OK, then look to check the slides (diaphragms) are not stuck as fuel will come of the Slide Needle as the revs go up
Also check the slide needles are in correct position using this guide
[Tutorial] How to adjust Carb Slide Needle (Tuning) – Hyosung GV & GT 125/250
// Meditation doesn't mean you have to sit still....
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Ordered : floats ,pins and needle valves this evening. I won’t have the parts for a couple of weeks. I am unclear where to measure the 7mm for the float height and what position the carbs are in. I the manual section I do have,it seems the measurements are with the carbs upside-down,17mm from the carb bowl seam/flange to the now top of the plastic float.
I really appreciate all the help
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Look for my reply with a picture here
This is the correct way because the manual has errors with carb information,
Adjustments can be done incrementally on the float tangs
Also, clear pipe , drain bowl loosened , look at the float bowl has _______ lines like that ______ , thats fuel height , you can have the clear hose against it to see if the fuel level is the same or carb is overflow on one pot or the other.
// Meditation doesn't mean you have to sit still....
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Also, clear pipe , drain bowl loosened , look at the float bowl has _______ lines like that ______ , thats fuel height , you can have the clear hose against it to see if the fuel level is the same or carb is overflow on one pot or the other.
The lines I have marked in blue is what you were talking about in the above quote?
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