'06 MC65 bogged acceleration from low RPMs

[cajones007]

All,

I recently bought an MC65 for my son and he is having an extrememly difficult time accelerating from low end RPMs - the bike bogs and he has to lighten up on the throttle.

In my discussions with a few 2-stroke bike owners, it was suggested that I move the needle up in order to dump more fuel on the low end. Unfortuntely, this didn't help. I thought I might need to adjust the air fuel mixture, but can't find any settings (specs) for the carb.

The bike startes easily, the plug appears to burning clean and haven't had an issue with fouling plugs. I pulled the carb, cleaned it thoroughly, but still have the same throttle issue. I have become very frustrated in troubleshooting this issue and thought it would be useful to see if anyone else might have some insight to share. I look forward to hearing your feedback and sugestions.

Chris

[SideshowBob]

Originally Posted by cajones007

All,

I recently bought an MC65 for my son and he is having an extrememly difficult time accelerating from low end RPMs - the bike bogs and he has to lighten up on the throttle.

In my discussions with a few 2-stroke bike owners, it was suggested that I move the needle up in order to dump more fuel on the low end. Unfortuntely, this didn't help. I thought I might need to adjust the air fuel mixture, but can't find any settings (specs) for the carb.

The bike startes easily, the plug appears to burning clean and haven't had an issue with fouling plugs. I pulled the carb, cleaned it thoroughly, but still have the same throttle issue. I have become very frustrated in troubleshooting this issue and thought it would be useful to see if anyone else might have some insight to share. I look forward to hearing your feedback and sugestions.

Chris

The pilot jet, not the needle, affect 0-1/4 throttle (roughly). Sounds to me like you need to richen up the the pilot jet. I would call Go Fasters or your local dealer to see if they can suggest a pilot to use (the current one should have the # written on it)

[roostafish]

I don't want to douche this conversation, but my friend has an '06 MC 65. He just picked it up, and it has literally less than 1 hour riding on it. It had similar problems as you describe, then it just stopped running. Turns out it's the ignition. Yikes. What a shame. It's off to Ricky Stator for repair because there are no parts on the shelf in USA.

[cajones007]

Ouch...ignition...man I hope that's not going to be the issue. I do have an update though; I was giving this some thought and realized I never considered the bike running to rich vs to lean. I pulled the needle and moved it up two notches and reset the air/fuel to 1/2 turn out (wanted to start rich). Cranked teh bike and the results were still pretty bad, so I started to lean out the air/fuel mixture a 1/2 turn until the throttle responded better. I ended up at 3 turns out (very lean if you ask me), uppeed the idle RPMs and the bike responds rather nicely with very little bog.

With that said, I think I need to still give the carb a good review - measure the float and maybe re-jet, to see if I can get a clean throttle response.

I am open to any suggestions on rejetting for more of an enduro rider then a moto racer, as my sonn likes to trail ride more than race. Thanks for everyone's input so far.

[roostafish]

It does sound like carb issues... Whew. That's a relief. That's a DelOrto carb, and the jets aren't exactly the same as the bigger ones, so no one here seems to have brass on the shelf. I'll bet you could easily go leaner on the pilot and needle to get results, especially for trail riding. You may just try leaning the needle all the way to the top clip position and see what happens. Even too fat of a main won't be much of a bother if he's not whacking the throttle all the way open all the time.

I wonder if RB-Designs has any magic for these carbs??

[cajones007]

We took it out for a trial run and the bike really struggled when he opened up the throttle (with it running lean). Basically, I had to run it rich again, and move the needle all the way down. Once I read up on how to adjust the carb, I realized I had leaned out the air fuel mixture. Once I open up the jet (running it richer) the throttle response was really good. We are going to take it out tomorrow and see how it runs underload and on the top end. Wish us luck!

[cajones007]

Well...it was the fuel mixture on the carb, of all things. Once I richened it up a bit, the throttle responded nicely. Once my son gets into cornering a bit better then it will be time to considered a richer pilot jet to get get better low end torque. However, for the time being...all is solved and well!