AberdeenBikers

Recently bought an 03 XR 650 for some enduro fun is in mint condition with only 5000km's however I had it out last week and had a bit of an off in the dirt ever since its been a bitch to start and wont rev past about 4k, also sometimes when kicking it over the kickstart goes rock solid and wont budge till I pull in the decompressor lever.

It does have plenty of power in the lower revs but just wont rev and starts backfiring etc when I open the throttle fully.

I've checked the timing thats all Okay and the carbs clean as a whistle I've also cleaned out the air filter and get the same running conditions with the fliter on or off. noticed last night that the headers are glowing red hot when its running also. I'm going to run it tonight with the exhaust off to be sure thats not blocked.

Any Ideas folks this ones starting to get on my t!ts just not sure if there's something stupid I should be looking at before I pull the head off it to check the valves

Sounds an awful lot like it's getting too much air.
Taking the airfilter out and having it make no difference is wrong too, the restriction from the filter should be noticable.
Engines not running up through the revs is another indication that there is too much air (Take the airbox off a carb / set of injectors and the engine won't run worth a feck.)
Exhaust glowing red hot (4 strokes do have hot exhausts) but, that sounds too hot = too lean = too much air.

make sure the airbox is actually sealed to the inlet of the carb.
look for splits in the rubber which may let air in.
check the whole inlet system for something obviously disconnected (might be a big thing, might be a small thing)

running a big single lean will get expensive, fast.

You havent squashed the exhaust have you?

airwave wrote:Sounds an awful lot like it's getting too much air.
Taking the airfilter out and having it make no difference is wrong too, the restriction from the filter should be noticable.
Engines not running up through the revs is another indication that there is too much air (Take the airbox off a carb / set of injectors and the engine won't run worth a feck.)
Exhaust glowing red hot (4 strokes do have hot exhausts) but, that sounds too hot = too lean = too much air.

make sure the airbox is actually sealed to the inlet of the carb.
look for splits in the rubber which may let air in.
check the whole inlet system for something obviously disconnected (might be a big thing, might be a small thing)

running a big single lean will get expensive, fast.

Forgot to mention had the plug out and it was badly coked up so I don't think its running lean I've also had the carb off a couple of times and checked over the airbox / filter and manifold all looks as it should

phatkat wrote:You havent squashed the exhaust have you?

I know the previous owner had been in about the silencer trying to "uncork" the power so I'm now leaning towards an upset in here possibly the silencer material has become dislodged causing a blockage that would make sense with the burning smell I was getting last night. I'm going to have a look at this tonight and just check over the airbox again looking for leaks

certainly sounds like a blockage with the hot gasses not disapating, maybe you took a clod of earth when you hit the deck it would explain why it runs ok at low revs

blackstorm wrote:Anyone experienced with big singles?

Is this what you're looking for???

Airwave wins!

had the silencer off no packing in it at all!

Had a good look at the airbox and found that the removable blank thats fitted and can be removed when bigger jets are installed had been dislodged by the impact. plugged it back in hey presto starts no probs and revs up to the limiter with shovels full of torque once again Ye Haww!

blackstorm wrote:Airwave wins!

had the silencer off no packing in it at all!

Had a good look at the airbox and found that the removable blank thats fitted and can be removed when bigger jets are installed had been dislodged by the impact. plugged it back in hey presto starts no probs and revs up to the limiter with shovels full of torque once again Ye Haww!

the farce is strong with this one . . . . .

Big Kneed Al (master of the emergency stop & "stand up" comedian) wrote:

blackstorm wrote:Anyone experienced with big singles?

Is this what you're looking for???

ahhhh the memories :)

Big Kneed Al (master of the emergency stop & "stand up" comedian) wrote:

blackstorm wrote:Anyone experienced with big singles?

Is this what you're looking for???

Nah been there done that!


Hasn't everyone

Only once