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ROTROD

XR 650L jetting.

5 posts in this topic

I was wondering if anyone has any recommended jetting for a 650l with a K&N filter,stock airbox without snorkel,FMF oval slip on pipe for approx. 1800feet above sea level?I looked through some previous stuff but maybe I missed it.Appreciate any feedback on this.Cheers!! :thumbsup:

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55/158 will do it for those mods with the stock exhaust. With your altitude maybe the extra richening the pipe requires will be made up for by the altitude.

PS have the standard-mods been done? (shim needle, drill slide)

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Hey thanks for the reply.I've read some of your posts,so thanks for your time.Hey,have you ever had a 650l with intermittent spark?Mine will run but then it seems like it has weak spark or else it is flooding.My carb has the plastic float so I can't change my float height,but I still have a 50 pilot with my screw at 2.5 turns out.Would that be to rich?(I'm waiting for a 55).Also,do you know the difference in sizes between Mikuni and Keihin main jets?Previous owner ran in a Mikuni main.The mik 147.5 is pretty close to the 150 keihin.I don't have a number drill set to check it,but I can check my pug.Anyhow,sorry to bug you and again,thanks for your help.Cheers! :thumbsup:

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I haven't had to mess with spark problems. The plug cap on the BRP -L (as I call it) has a resistor, and has been known to fail. Try putting a good quality plug cap on it.

On some coils, the plug wire is held to the coil by a screw-on collar. If the L is like this (haven't noticed myself) it can be worth it to take it off and make sure there's good metal-to-metal contact to the wire.

I have no ide on the mikuni jet sizes.

Can you give a more detailed list of symptoms?

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I'm gonna try to check it out today or tomorrow,and I'll pay particular attention to what it does.The motor was recently tore down and honed the cylinder,put back the stock piston and rings(but scuffed the old rings with fine grit sand paper 4000)and replaced the cam chain,camshaft and re lapped the valves.It looked like it had overheated and the intake valves had hit the piston,possibly from the chain skipping a tooth.The valves were straight,the guides looked good,and it has new valve guide seals as well.When you rev it up,as the revs drop it pulls a bit of oil in under vacuum,but it happens quick enough that it may be oil past the rings under compression.It is hard to tell.I don't have a leak down tester,but I'll try to get one.Anyways,I'll contact you on this later.And buy the way,if you are wondering why I didn't bore out and get new piston/rings,the pin bore on the con rod was slightly burnished,so I thought I would run ér till it needs it real bad.(budgets...suck)Thanks.Cheers! :thumbsup:

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