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Power on the main jet

  • Thread starter Thread starter Oliverstrother
  • Start date Start date
I am just trying to rule out the ignitor as the problem and you did!
12k rpm in first?? I missed a shift the other day going from 3 to 4- tach appeared to hit 10 k, I had visions about spitting valve shims, so I took it easy after that.
 
I must be missing something here. Stock main jets are 110. There is no way I can see that you are running 160 MAIN jets. 130 would be a big increase over stock. Are you playing with the wrong stuff?
 
dyno jet kits come with two options 155s and 160s.

Fuel flows throughout the jet based on the size and the pressure difference across it. Changing pods and exhausts etc, change the pressure differential so the size has to be changed to compensate.

Right now its running 160s, as recommended by dynejet, The plug looks as though its running lean after a highway run at full power.

http://youtu.be/m_13l3Zs4ao

heres a video of the power performance, it struggles at high rpm under load and kind of surges.
 
Put larger main jets in it.
I hope it fixes your problem.
Remember that DJ mains are not the same as the Mikuni mains.
Did your kit include the brass inserts for the main air jet?
 
"....and its very very good on anything except the main jet."

"Yes it will go 40mph in third easily. The only wall I hit is around 9k rpm, under heavy load perhaps in 3rd gear or higher. It kind of goes 8k, 8.5k, 8k, 8.5k, 9k, 8.5k, 9k then kind of top out there.

Main jet, needle or airflow thru those odd dual pods- vacuum pistons have to open wide and be steady at increased loading.
 
Cheers fellas, I guess I'll have to go back to dyno jet for some larger DJ's. I had no idea they were different. If only it were simple. Eh?
 
I am with Chef that something is missing in your formula. Most probably intake manifold O-rings or that air jet. Anyway, Dynojet 160=150 Mikuni. To help your stumbling block, I would go to a Dynojet 166 or Mikuni 155 main jet arrangement.
With pods and stock exhaust, I only needed 120 Mikuni (128 Dynojet) main jets on a 650 at Sea level. :confused:
 
Hey fellas,

Spoke to the guys at dyne jet who suggested i check the movement of the slides and test the performance without the air filters on.

I check the carb slides and cylinder 1 felt like it had some kind of obstruction, nothing serious, but certainly not smooth. I dismantled it and didn't find any damage. After reassembling it moved just as smooth as all the rest.

Performance without the air filters is much improved, but the problem is still there. Is this indicative of anything?

heres a video for those interested. https://www.youtube.com/watch?v=mdMgW9cpMB8&feature=youtu.be


Cheers,

Oliver.
 
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So letting more air in (filters removed), performance is "much improved" implies to me that your main jet is oversize for your filter setup.
 
Bang on.

Slapped in the dj155's the kit came with and it feels better. Although I haven't had chance to take it out properly.

Will try this today. And let you guys know how it goes.

Interestingly the dynojey guys mentioned that spark plug colour tuning is harder to do these day due to the additives in the fuel.
 
float heights were set with a vernier, I haven't got the kit to set them on the bike. The were set about as accurately as your going to get without a nipple and a tube.

I haven't got the kit to sync the carbs either. that was done with gauge wire under the throttle valve.

155 jets are working well, now. but rain is preventing me from getting her on the highway for a prolonged full power test.
 
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