Trying to Raise the Dead ('85 XR600R)

[fat_boy_on_CRF450x]

I sold my '85 XR600R to my buddy in '93. On his second outing to Glamis he went over the bars and knocked his two front teeth out. The bike has sat in his garage unstarted since then (10 years). I have been bugging him over the years to sell it back to me as a spare bike. He finally relented a couple of months ago and it's in my garage now.

The bike's in really good shape cosmetically. I have replaced almost every part in both carbs - jets, needles, needle valves, etc. (bikebandit.com loves my money). I couldn't get any spark, so I got out my tester and found I had to replace the pulse generator. I finally got spark but it was weak so I put in a Ricky Stator. Spark seems fine now.

Fortunately, my buddy had drained the tank before he stored it. It still had a bunch of dried up varnish chunks in the bottom. I rinsed and scraped the tank out a few times with a long screwdriver and got the junk out of it. I took out the petcock and cleaned the screen out.

I got it to fire today, but it is hard to keep running without the choke on. It dies when I twist the throttle quickly unless the rpm's are up kinda high. It is popping a bit when I back off on the throttle. It is responding to adjustments to the air screw but I can't seem to find the right adjustment to get rid of the popping.

When I rode it down the street to put a load on the engine, it started popping a lot and died when I let off the gas.

I definitely am not the most knowledgeable mechanic out there. Am I doing something wrong? Should I be looking elsewhere like the valve clearances (which I haven't checked yet)? Any thoughts?

[Jigggawatt]

Take air or contact cleaner and blow through your jet passages. One of your pilot cicuit's are plugged

[Shawn_Mc]

Sounds like the air screw is open too far...Close it all the way and open it back up to one turn.

[fat_boy_on_CRF450x]

Thanks for the suggestions. I'll try both.

[XR6's_rule]

I'd also check the float level in those twin carbs, they are quite succeptible to float level setting. As well as this check the opening clearance adjustment for the secondary carb, this also makes a fair difference.

Cheers

Mark.

[fat_boy_on_CRF450x]

How do I adjust the float level on these carbs? Thanks.

[Shawn_Mc]

You've gotta bend the tab that the float needle rides on. Its easy. You just take the bowl off and hold the float up with your finger and turn on the gas. raise the float until the fuel stops. Thats the level. Then you bend the tab a bit to go the direction you need. It doesnt take much of a bend to move the level a lot...

I asked about the level and someone told me it was 14.5mm. It cant be. 14.5 puts the float into the body of the carb. I set mine at around 17-18 I think. Seems to work fine.

The carbs are super sensitive to the float level though...for the longest time I was messing with the screw trying to get the idle mix right. It wouldnt idle or even start unless the fuel screw was fully bottomed. Finally I raise the float level way up. Now Ive got a quaility idle with the screw at about 1 turn out and it'll still start (sometimes with ease..sometimes not).

[fat_boy_on_CRF450x]

Thanks Shawn Mc, XR6 and Jim1234. I took off the carbs today, pulled out all the jets, blew them out and blew out all orifices in the carbs. I checked the opening clearance adjustment for the secondary carb and it was fine with the idle setting I had on the carbs. I must have gotten something in the carbs when I was putting the airbox back together the first time.

I put everything back together today. Kicked it about 8 times and it roared to life with no popping at all and no bogging/dying when I twisted the throttle. I let it warm up and adjusted the airscrew. I ended up at 1 1/2 turns out. I set the idle and checked the opening clearance adjustment for the secondary carb and all was well.

I took it for a run down the street and it is running perfectly! Absolutely no popping on decel (which I have on my stock CRF450X). This thing is better than I remember! I live in a very quiet gated neighborhood so I didn't get a chance to run it too much.

Based on my initial reaction, I almost wish I didn't buy my 450X now (almost). I may find myself riding my old BRP more than the new bike.

Thanks for all you input. I'll get some pics and post them soon.

[Mantrasonica]

Flog it!