[PatrickB]

I know this is a Honda forum, and I do have a Honda TRX 350 4 x 4, but I'm currently working on restoring a Yamaha 225dr three wheeler. I recently installed a new top end, the valves are set and gapped per the manual, and timing is set per the manual.

The bike will start on the first pull and purrs like a kitten, and you can rev it from low to high but if you hold down the throttle passed low range it will start to bogg. I have the rear wheels off the ground and off of the bike so that there is no resistance and it still does it. It will go through all of the gears just fine but starts to bogg as you keep trying to give it throttle.

The carb is getting plenty of fuel, the float height is correct, air fuel mixture screw is properly set, and the carb is clean as a whistle..I double checked it. I also tried different combinations with the air fuel mixture screw and needle height position but nothing really changed. Also if you flip the choke on it will start to die after a few seconds just FYI.

I'm starting to think it's either something electrical or possibly the main jet is not allowing enough fuel for some reason? I am 99.99% sure that the carb is all stock and original. The new top end kit I installed is 6cc' slarger than OEM so didn't think rejetting would be necessary?? I'm at a loss so any other ideas or suggestions will be greatly appreciated, thanks guys!


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[b52bombardier1]

Using a good, 25-30 buck multimeter and not the cheap giveaway meters from Harbor Freight, etc - what do you see for both DC and AC volts at the battery posts with the bike running at half throttle?

Rick

 

[PatrickB]

Using a good, 25-30 buck multimeter and not the cheap giveaway meters from Harbor Freight, etc - what do you see for both DC and AC volts at the battery posts with the bike running at half throttle?

Rick

I'll have to check... not sure if it matters but electric start is not working on this bike, battery is new though. I'm pretty sure the generator is good because the headlight gets brighter as throttle increases.

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[Goober]

Magneto pick up?

Is spark plug sooty as in a rich condition?


was surprised to find the wide range of jet needles for this. Can you try a different one to see if it changes throttle response?

 

[b52bombardier1]

But is the bike lighting getting brighter because the regulator / rectifier is allowing the voltage to go too high? The rectifier could also have blown diodes that leak alternating current.

Rick

 

[PatrickB]

Magneto pick up?



Is spark plug sooty as in a rich condition?





was surprised to find the wide range of jet needles for this. Can you try a different one to see if it changes throttle response?

The spark plug is a little black indicating a rich condition. I've also tried different needle positions and nothing really changes.


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[Goober]

Good you tried different positions–sorry I meant main jet. The 250 manual also says the needle jet can be changed; this is a two stroke also?

 

[TRX2fiveO]

Take the filter cover off and see if it gets worse or better

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[PatrickB]

Good you tried different positions–sorry I meant main jet. The 250 manual also says the needle jet can be changed; this is a two stroke also?

It's actually a four stroke 225cc.


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[PatrickB]

Take the filter cover off and see if it gets worse or better

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I tried that and it seem to get a little worse.


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[TRX2fiveO]

Too lean...

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[PatrickB]

Too lean...

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The spark plug is black so I figured it's running rich..

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[TRX2fiveO]

If you took the cover off and it got worse it's too lean. You added even more air when you took the cover off. Have you cleaned and replaced the air filter? also make sure the snorkel air intake tube (if it has one) is connected.