'85 Big Red misses at high rpm

[Hayward]

Stumped here. Just cleaned the carburetor since trike had been sitting up with old gas. While trying to get the air box out, the green colored module wires connected to the voltage rectifier pulled hard and started leaking oil. ? I just pushed the wires back, the oil quit leaking (or ran out) and I proceeded the carb removal. After replacing a clean carb back in, it fired up and sounded good until I reved it up. It has a steady miss at WOT. Idle and mid-range throttle sounds good. Could the wires I pulled have anything to do with the high rev miss ? I soaked the carb, sprayed cleaned all jets, and blew compressed air and felt good about the cleaning. Any suggestions ?

[goump1995]

Check the spark plug gap.

[Chazz of Blades]

Check Spark
Check Valve Clearance
Recheck Carb
And for the love of all that's good: If you EVER think you may have ran out, CHECK YOUR OIL!

[Hayward]

Thanks for the replies guys. I have replaced spark plug gapped at manual specs (.024-.028). Also Chazz, I've checked valves and set at .003 . No help. Have good spark though, not really big and fat blue but steady. The oil I lost came from the green plastic wire connector with yellow wires going to the voltage rectifier.

[Scootertrash]

And for the love of all that's good: If you EVER think you may have ran out, CHECK YOUR OIL!

That there is sig line material!!

[Hayward]

That there is sig line material!!

I don't get it, Scootertrash .?.
I removed and soaked and cleaned out carb and jets again. Still has steady miss at WOT. Tested coil and pulse gen. and tested to spec. I'm thinking a firing problem, I need help, please !

[kb0nly]

Check the spark advancer, mine was doing the same thing, the advancer was shot and wobbling on the camshaft, just plain wore out.

[Hayward]

Check the spark advancer, mine was doing the same thing, the advancer was shot and wobbling on the camshaft, just plain wore out.

Thanks,kb0nly. I haven't thought about that. Will check tommorrow.

[kb0nly]

Thanks,kb0nly. I haven't thought about that. Will check tommorrow.

Check the gap on the advancer to the pickup as well, it shows how to do it in the service manual which is available for download on this site. I would pull the advancer and clean it all out and lubricate it all. When i pulled mine out it was full of a rusty/oily residue, i cleaned it all out with a shop rag and some brake cleaner. Just make sure you mark the position of the plate holding the pickup on the advancer housing. I took a small chisel and put a reference mark on the edge of the plate it sits on and the aluminum housing. But even just marking it with a marker so you can get it back together in the same spot would be a good idea. If you have access to a timing light i would also check the timing as misfiring under throttle is usually an advance problem...

However, don't rule out weak spark. Also put in a new NGK plug and check the gap, and check your valve adjustments as well, these items all affect it and cause missing at high speed.

[dougspcs]

Check the spark advancer, mine was doing the same thing, the advancer was shot and wobbling on the camshaft, just plain wore out.

This is an 85 which makes it a 250, no advancers on this animal..you're thinking 200cc

Ignition advance is totally in the CDI unit..consider a possibility that it may be faulty..consult a manual for the test proceedure.

[kb0nly]

Oops brain fart... Ok but he should still check the pulse generator.

[Chazz of Blades]

One issue that I had with my 250 was the choke cable binding a bit, see if the handlebar lever actuates all the way back and forth smoothly.

[Scootertrash]

I don't get it, Scootertrash .?.
I removed and soaked and cleaned out carb and jets again. Still has steady miss at WOT. Tested coil and pulse gen. and tested to spec. I'm thinking a firing problem, I need help, please !

A sig line is at the bottom of your post where you can put a statement that shows up in every post you make. Chazz's comment
And for the love of all that's good: If you EVER think you may have ran out, CHECK YOUR OIL!

Would make a good sig line.

[Hayward]

You may be on to something, Chazz. I broke (and repaired) the plastic handlebar switch trying to engage the choke. It very well could be binding. I'll check that out.

kb0nly, I did check the pulse generator and it ohmed out OK. Replaced with new NGK and gapped @.025 . Valves have been set at .003. I guess CDI will be next test. Thanks!

[kb0nly]

Good deal, definitely check that choke. And sorry for the brain fart earlier, seems like there has been a lot of 200 posts on here lately with ignition problems so my brain was stuck... LOL

CDI isn't all that testable, its swap it to check it in my opinion.

[Flyingw]

Like KB said, the CDI is not testable. its fully transistorized and unless you have the special electrical gizmos, you can't test it.

[JustEnough]

I had no spark on my 85 250ES so I carefully wire brushed the electrical connections and smeared dielectric grease on the connectors before reconnecting. Since I could not get a brush up into the hooded female connectors, I gave them a blast of compressed air to get the dust out. When checking the tab connectors on the primary coil, I found the black one was just between the rubber boot and the connector. I now pull the boot back, securely fasten the connector and then pull the boot over to make sure it is on right. I think that loose coil connector was the main problem.

Now I have a white hot spark and the Big Red starts real easy.

[loosescrewkid]

my 200s did that as wellall i had to do was tune in the carb. not saying i its going to fix it. thats just all i had to do