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New Mikuni, some problems though

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96 xr4

Wiseco 11:1 440

WB E series (original)

Ground Header Welds

Snorkel Removed

Uni Filter

Got my pumper in today from Thumper Racing. The bike does not run well at all. I am going to check for air leaks tomorrow but until then I wanted to run the habits by you guys. Pull the choke and the bikes starts with a very high idle. As it warms up, you can slowly let the choke out but if you go too fast it dies. Once it will idle without the choke, the RPM's are what you would expect for an idle. If you jab at the throttle, it will bog and usually die. If you roll it on it will keep up but sometimes stutter. If it is idling and I reach around and push on the pump rod, it will cause the idle to dip and if do it quick enough, will kill it. I can turn the slow jet from 1 turn in to almost falling out without much change. I do not know what jets were shipped but they were supposed to be set up for my larger bore at pretty much sea level with that exhaust. I will dig into it tomorrow to find out what the jets are. I did try and run it around a little bit but it kept wanting to die so I cut the trip short.

So what do you think, rich or lean? ...or something else?

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I dont claim to be an expert, but sounds like it could have some trash or some other debri in it, might want to tear her down and clean it out good and see what jets you got. good luck:thumbsup:

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Not a diagnosis, but here are some starting suggestions. When I got my mikuni from TR it was jetted 12.5/125. That's incredibly lean. Try 15/130. Fuel screw set @ 2.5 to 3 out. Check the acc pump screw. It should be all the way in and use a little loctite, as it can definately back out. Good luck, when you get it right you'll love it. BTW, mine is 426, stock cam, ground header welds, no snorkel, K&N filter, and a revloc auto clutch just for fun.

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Not a diagnosis, but here are some starting suggestions. When I got my mikuni from TR it was jetted 12.5/125. That's incredibly lean. Try 15/130. Fuel screw set @ 2.5 to 3 out. Check the acc pump screw. It should be all the way in and use a little loctite, as it can definately back out. Good luck, when you get it right you'll love it. BTW, mine is 426, stock cam, ground header welds, no snorkel, K&N filter, and a revloc auto clutch just for fun.

So, you have the revloc, how do you like it? I cannot believe how pricey they are. I guess when you are the only game in town, you can hike em up. They are 200 bucks more for the XR than the CRF, I'll bet simply because Rekluse makes a CRF auto clutch, but not one for the XR.

That fact alone prompts me to never, ever, buy anything from Revloc cause it seems like they are price gouging.

Sorry for the hijack, please continue on with helping this poor fellow out with one really awesome carb.

I was lucky, installed my Mikuni, and instant difference. Superb throttle response, but the first time it was hard to start. Every since, it's heaven.

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sbabs,

I put the revloc on in 2002. I don't think rekluse was around then. I also have a rekluse on my 2003 ktm450exc woods bike. I gotta say I love the autos, but I really like the revloc the best. I also have LHRBs on both bikes. The combination is great if you like really technical type riding. The XR has a 3.8 gal tank, Baja kit, street plate and 16/45 gearing and is used almost exclusively for dual sport riding. It's way too much fun.

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Is the Mikuni from TR a TM36-50 pumper? I didn't know they sold a kit for the XR. Did it come with the machined bore adapters too?

If you're not over 6000' elevation, the 130/15 jetting is usually the proper setup. And like was mentioned before, turn the pump rod activation timer screw all the way in. It's that screw with the spring under it that is screwed into the white plastic arm.

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I installed mine last week and it seems to be working fine.. although I haven't really been able the ride the bike much yet.

One thing you said was that the bike would stall if you manually pushed down on the pumper rod.. That would make sense because the Pumper is spraying gas at the closed "intake door". I think that is why everyone sez to delay the pumper activating as long as the adjustment will alow so the door is open when it starts to spray..

I know "intake door" isn't the proper term but that's the best I can describe it.

As far as the rough running, sound like an air leak is possibly the problem.

I bought mine from xrs only and it came with the adapters already on.

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I called TR and the guy said it was a 130/12.5. His initial impression was that the jetting shouldn't be that far off from how I was describing so he definately suggested checking for an air leak around the insulator first. He did say that the next jet in the line would be the 15

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The way you're describing the choke operation does not sound like a TM 36-50. That choke knob is either on or off. There is no slowing releasing it.

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I am almost positive it is a TM 36-50. When I say that I am slowly letting it out, I mean I am keeping my hand on the knob and holding it. Also, this carb does have an aluminum adapter on the airbox side. I did spray some WD-40 on the insulator boot while it was running and could not get it to sputter so the jury is still out concerning an air leak possibility.

I took it out for another spin this evening and the thing was popping like crazy and kept wanting to die. You know I kind of figured that if the mixture was this lean it would help if the throttle was rolled enough to use the pump, but it does not seem to help.

Yes, the actuator screw is turned all the way in.

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That still doesn't sound right. When the choke is applied, the knob is PULLED out til it clicks into a detent. To take the choke off, you PUSH it in. You should not have to work it like you are doing, milking it between on and off to get it to run. I would put the 15 pilot in it, readjust the fuel screw for best idle and make sure the idle knob is set fast enough that it WILL idle when the choke is turned off.

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