Fitting CRF150 exhaust to GY50 200 - any tips??

[Frog]

Hi everyone

I have bought a genuine honda CRF 150 complete exhaust off of fleabay. (Equivalent to $22!). I am planning to fit it to my Lifan GY5. Has anyone any tips?

Cheers

Frog

[FastDoc]

I think it's been done, and was a simple installation. You may be able to search for the thread... I doin't recall the specifics. :D

[katoranger]

I believe it is near bolt in. Might need to adjust some of the mounts.

[Frog]

Thanks FastDoc and Katoranger - just found an old thread - looks easily doable (famous last words....).
:D

I'll post some pics once I get down to it. I may even consider having a go at gas flowing the head (or at least tidying up the exhaust port) - if I can find my old flex drive and burrs etc.

Cheers

Frog

[BrianW]

I purchased a Mini R4 exhaust off of forum member Katoranger. The pipe seems to be designed for the crf150 originally. It bolted directly on a Lifan GY5 with no problem. You just have to fab the rear-most mount to fit. I used a piece of flat steel; Very simple to do.

[Frog]

Thanks Brian - sounds quick and easy - looking forward to getting it done!

Frog

[Frog]

Well in the end not particularly quick and easy! But is on there looking good, sounding good, bike going well BUT lots of popping and banging when closing the throttle fully from high revs. I have checked for air leaks up stream of the silencer and all good - I'm guessing it is very weak / lean on the over run.
:(

Have played with the mixture screw but no good. I suppose it needs a larger pilot jet..

Does anyone have any other thoughts or know if the pilot jet is replaceable on the carbs these bike use - Lifan GY 5 200cc?

Cheers

Frog

[Weldangrind]

Both jets are quite likely replaceable. I found Mikuni jets at the Yamaha dealer and Keihin jets at the Honda dealer. Which type of carb do you have?

[ejcycles]

Hi Frog
2 suggestions... first check the valve adjustment make sure the are @ 0.003". If the valve adjustment is correct then you need to jump up size on the main jet.

[Frog]

Thanks for the thoughts on this.

I will check the valves.

I think it has to be the pilot jet that needs increasing as the main jet will not be doing much with the throttle fully closed. The carb is I think a round slide keihin clone - but I'm not sure - will take it out today and have a look...

Thanks

Frog

[Frog]

Problem Cured :)

Checked valves and they where fine. Took out carb and then removed pilot jet - tried to get a size larger at three local Bike shops but no one had seen a jet like it (carb is Sheng Wey) .8O

I could find nothing similar on the net either...

Needle jet said it was a 40 and a 0.4mm drill was a little tight. Took it out to 0.42 mm and replaced everything. With drills this fine you have to be very careful not to break them. I can now induce pop or two by shutting off from high revs going down hill - but on the flat no popping!

I think this means its about right :D

CRF150 Exhaust is good - quite mellow and 'bassy' without being too loud. Silencer was not as dent free as the seller claimed but looks OK.

Bike is breathing better and performing noticeably better. The new set up is also a few pounds lighter than the original.

Frog

[JTCAndrew]

Did you get any pictures for us? Sounds like you got it tuned......

[SpudRider]

I'm glad you got the exhaust installed, and the jetting correct, Frog! :)

Spud :)

[Weldangrind]

Needle jet said it was a 40 and a 0.4mm drill was a little tight. Took it out to 0.42 mm and replaced everything.

Do you mean the pilot or main? If that's the main, it's really small (when compared with the 1.1mm jet in my Mikuni). I don't have a bit much smaller than that, and my pilot jet is stamped 25 (which I presume to mean .25mm).