hot cams exhaust cam and crappy idle

I'm going to look at a wr426 2001 tomorrow. Speaking to the owner he says it has a hot cams exhaust cam fitted, the previous owner fitted it not him but he says he's barely ridden it..... Too fast apparently. Anyway, the reason I mention it is because he says it has a rough idle, backfires and will cut out if the revs arnt maintained, I'm just a bit worried that whoever put that hot cams ex cam in ballsed up the timing a little..... Or am I reading to far into this and it could just need a carb clean. He did say its sat for a while so the fuel will be stale.

Also anything in particular I should be looking out for when I look at it tomorrow, common problems etc


No idle is typically a clogged pilot or pilot passage, or a bad fuel screw.


Once above idle, under load, if it runs well, it's not a timing issue.


Deceleration popping is also a lean issue, usually the pilot, or a leaking hot start.

That's the answer I was hoping for, makes life a lot easier. I'll get a new pilot jet and carb rebuild kit and pull it all apart and re-set it, if I buy the bike.

Thanks bud

A carb rebuild kit only replaces gaskets, which usually don't go bad for decades


Uncork the bike, and rejet per the FAQ section

I bought the bike yesterday. Bloke wanted $2,200, i managed to get it for $1,700. Just needs a rear shock (he gave ne his spare good one), carb sorting out and none of the lights work so need to look into that. Otherwise its quite nice, got '05 plastics, tank and rear subframe. After market exhaust and new piston, rings, timing chain and hot cams exhaust cam. Pretty happy with it so far, its a shit ton faster than the xr thats for sure. I had a look at them online and you're right, they do only include gaskets. Only reason I thought they had everything was I bought a carb rebuild kit for my old xr250, that had a new main, pilot, float valve, needle and all the gaskets.

I went to my Yamaha dealer today to try to get new jets but they are just a bunch of WA*Ker's, last time I went in to try and buy a rear tyre for my xr I was told "sorry, we don't do tyres for Hondas....." Today I asked for jets for the wr, they have none in stock and were less than willing to order some.... Gave up on them.

I found a bottle of "carb cleaning dip" in the shop though, going to strip the carb and leave the carb and all bits soaking in this cleaner for 8 hours, hopefully that and a bit of toothbrush work should do the trick.

Does anybody have any tips for making the clutch pull lighter? I've got a new cable on order but I've read that they're a heavy clutch anyway. Hydraulic conversion is too pricy at the moment.

I pretty much already know the answer to this but might as well try my luck, does any aftermarket company make a longer actuator arm, or maybe a different holder on the handle bars that has a different type of leverage system to make it lighter....?

Don't soak a FCR carburetor in carby clean. The mid body seal can be destroyed, the seals can be bought for later model FCR's but not for the early ones like yours. People have been able to cobble together a gasket out of the two later model FCR mid body seals but this is by no means a guaranteed fix.

Edited by boston460

Yep , one of the things I learned from KRANNIE. Never use Chemdip or Carb

cleaner on those carbs ....ever !

You need a new pilot jet, unless you own a sonic parts cleaning machine.

The rest will clean up.

Do NOT NOT NOT soak the carb in regular carb solvent body or you will destroy the carb

If the motor has hours on it, go ahead and replace the needle jet (emulsion tube) and apump diaphram and slide plate seal.

Get an R&D fuel screw too.



Edited by KRANNIE

That's the carb dip out of the window, thanks for the heads up guys, probably saved me a hell of a lot of hassle.

So what would you recommend using to clean the carby?

I'll look up some jets online and try to get them ordered now, thanks.


Unless the inside of the float area is all green or brown, you should not need to do anything but clean it with simple green, fishing line, and compressed air.

The tight spots are the apump system and  brass nozzle, the pilot jet, and the passage above the pilot jet.

Everything else will be fine.

The fishing line is a brilliant idea! So no chemicals, sprays, cleaners of any sort?

First time I've cleaned a carb out dry, normally I'd use a toothbrush and spray carb cleaner, that's why this is throwing me a bit.

I'll check out the website now mate thanks

If you need a tooth brush to clean the carb on the inside, you best soak it in simple green for  a few days.


Use spray brake cleaner.


Spray carb cleaner can be used with caution, but it will melt the slide plate seal, and can damage orings if left on for a long time

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