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Pre-ignition?

Featured Replies

it seems to be an topic with plenty of discussion , so now its my go .

i have an 04 270 rev3 . when the throttle is 3/4 open on climbs or constant going the motor pings .

the bike runs on 98ron fuel , 1.5% oil putoline mx5.

carb is set up as follows

main 150

pilot 30

needle 5c23 on middle position

2.0 slide

a.s. 1 1/2 turns ( i have tried to correct on this but the problem is higher up the fueling than the pilot)

could it be a squish clearance too tight?

it feels like its too lean on the needle

any advice ,or how you cured yours would be appreciated.

  • Author

how is the ignition timing set? is it done via a stobe whilst running? or is it static set using a dial gauge?

anyone know what the correct values are?

there are ignition timing diagrams on JLI's website.

www.thetrialcompany.com

If you have a bike which is <03 model or which is a 200 then it will have a different stator so don't set your ignition timing up like this! :D

Bob

post-1035-1131823107.jpg

I had the exact same problem on my 270. Fixed it by going up one size on the pilot jet (to 32.5). Jets are cheap so it might be worth a try (best place to buy Mikuni jets is from Allen's Performance.)

  • Author

thanks for the advice, i will try the pilot jet first.

do all 270's suffer like this?

do all 270's suffer like this?

I've heard of a few with the same problem. I'd also check your ignition timing as descibed elsewhere in this thread but I did that first on my bike and it was spot-on. No idea why the pilot jet would have any effect on a problem that only manifests itself when you're hard(ish) on the throttle but I'm sure someone more mechanically knowlegable than me will be able to explain that :D

Edited by neonsurge

  • Author

well there you go ! changed pilot jet and cured! still cant understand why , but its fixed .top advice neonsurge. anything else i need to know re the 270?

anything else i need to know re the 270?

Yep. They're far too powerful (for me, anyway :rolleyes:) Definitely an expert's bike. I got rid and bought a 250 :unsure:

  • Author

that has not escaped me either, mind you i can blame poor results on the bike!!

Mmmmm

I have been telling people for years the importance of the pilot jet.

Keep in mind the pilot jet is still working at all the stages of throttle opening.

Glad to see you have fixed the problem.

BillyT :rolleyes::unsure:

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