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thought jetting, but now it's electrical. thoughts or ideas?

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i started a thread about jetting because when i hold the throttle at a constant, it would "hickup" or "sputter".

 

it's herehttp://www.thumpertalk.com/topic/1057136-direction-needed-on-jetting-xr600-bastard-bike-1988/

 

last night i changed from a 68 pilot to a 65 and no change. from a 168 main to a 165, no change. i still dont here a change when messing with the air screw. so may still be fat on the pilot, but don't think thats my main problem.

 

on advise from davitbogart in the previous post, i got out the manual and started checking electricial. heres what i found.

 

tests found in the manual to check CDI

 

ignition coil primary, blk/yel to grn .1 - .3 ohms         i have .3

ignition coil secondary, blk/yel to hi tension (no cap) 7.4k - 11k ohms      i have 3.2k

exciter blk/red to ground 230 - 320 ohms      i have 256 ohms

pulse generator blu/yel to grn/wht 360 - 440 ohms      i have .431k

 

coil primary .1 - .3 ohms      i have .2

coil secondary 7.4k - 11k ohms      i have 10k

" w/o cap 3.7k - 4.5k ohms       i have 3.1k

 

it appears my pulse generator is bad, yet it still runs? i have a generic ignition switch on the pulse generator wire to deter theft. i did unplug the pulse generator from the harness and got the same readings, so its not the switch.

 

i need to recheck the blk/yel wire from the plug to coil. it seem to have too much resistance.

 

i do not have a motorcycle timing light to check advance.

 

can it run with a bad pulse generator?

i don't understand how the CDI advances timing?

do you think all it is, is the pulse generator?

 

thanks in advance!

 

heres my home edited wiring diagram. the reg/rec and batt is from ricky stator

 

88-90_XR600R_wiringb_zpsf46075b8.jpg

 

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Find a long straight stretch, either of road or of flat dirt.  Cruise along at steady throttle at all different throttle positions -- at 1/8 throttle, 1/4 throttle, etc.  Do you get the same sputtering at all positions?

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yes, i get the same "sputtering" at different throttle openings. i even get it in neutral just holding the throttle open. bike not moving. "cutting out" sporatic might be a better definition?

 

i should mention, i bought this bike for cheap, adj valves and cables, checked for good compression, new gas, rebuilt carb, got it started and rode down the street a block or so, then tore down to "modify" its looks. i have no real knowledge the condition of the motor or its history.

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Double check to ensure any grounds to the frame are tight.  Not sure if you did anything with the electrical such as remove or clean it, but if that isn't tight, it can cause issues similar to what you are explaining.

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My mate has the same problem with his 2009 yz250f , he tried everything and ended up getting a new Cdi unit. Which worked for a while now it's spluttering and popping again.

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I'd disassemble the engine's top end to investige.  Mechanical problems can manifest as all sorts of strange running behavior.  It's probably more time and money efficient to do that first.  Otherwise you may spend months of frustration and cost in trying to diagnose and replace all sorts of peripheral parts.

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Double check to ensure any grounds to the frame are tight.  Not sure if you did anything with the electrical such as remove or clean it, but if that isn't tight, it can cause issues similar to what you are explaining.

i painted the frame, so i will check for good continuity between frame and engine.

 

thanks

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I'd disassemble the engine's top end to investige.  Mechanical problems can manifest as all sorts of strange running behavior.  It's probably more time and money efficient to do that first.  Otherwise you may spend months of frustration and cost in trying to diagnose and replace all sorts of peripheral parts.

what would i be looking for? i will try to video it with my phone tonight and post on here. that might be a better discription of whats happening. i will try to figure out how to do that.

 

thanks

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i painted the frame, so i will check for good continuity between frame and engine.

 

thanks

 

Check the ground under the seat,,sand off the paint and re-install the bolt......engine does not ground through the frame,,it grounds through the ground wire bolted to the rear of the starter........

 

B

Edited by brianhare

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i didn't have time to video, but did check that the engine case had good continuity to the frame.

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Run a second ground wire just to be sure plus it doesn't hurt a thing. I put them from a bolt by the head(pick one) and run it up to either one of the cdi mount bolts or the coil mount bolt. it gives the electrons a "choice" to ground. I also go through my entire harnesses and clean all connections(blow them out with compressed air to get as much dust/dirt out), then reassemble with dielectric grease. I also pull each connection back apart 1 or 2 times just to make sure good connection then.

 

I sure wouldn't take the motor apart just to look for something that may or may not be wrong. Verify that it is internal as much as possible before going to that extreme.

Edited by jjktmrider

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Run a second ground wire just to be sure plus it doesn't hurt a thing. I put them from a bolt by the head(pick one) and run it up to either one of the cdi mount bolts or the coil mount bolt. it gives the electrons a "choice" to ground. I also go through my entire harnesses and clean all connections(blow them out with compressed air to get as much dust/dirt out), then reassemble with dielectric grease. I also pull each connection back apart 1 or 2 times just to make sure good connection then.

 

I sure wouldn't take the motor apart just to look for something that may or may not be wrong. Verify that it is internal as much as possible before going to that extreme.

 

ok, i'll try adding another ground.

 

thanks

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pulse generator blu/yel to grn/wht 360 - 440 ohms      i have .431k

 

it appears my pulse generator is bad, yet it still runs? i have a generic ignition switch on the pulse generator wire to deter theft. i did unplug the pulse generator from the harness and got the same readings, so its not the switch.

 

 

 .431k is 431 ohms :doh: just caught this. i wonder why my meter reads sometimes in ohms and sometimes in K ohms? appears the pulse generator is fine

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 .431k is 431 ohms :doh: just caught this. i wonder why my meter reads sometimes in ohms and sometimes in K ohms? appears the pulse generator is fine

Dunno..I have a meter hooked up permanently to the batteries on my boat so I can keep an eye on charge etc..Last Xmas I was out around some islands and was having all sorts of odd readings..I assumed it was a bad battery in the boat so I got a new one..Was the battery but not the boat one..the meters battery was had it giving out bad readings..Something to contemplate..

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well its been awhile, been selling one house buying another and moving, and all the crap that goes along with that, but i'm back at my problem child xr600.

 

ok, so if everything ohms out, and it runs , do i assume the cdi is good? acording to the manual, you check the cdi by ohming out everything else. if the cdi is bad, will it just not run at all?

 

my "cutting out" happens at any throttle opening. i don't even have to be riding it, it will do it in neutral on the kick stand.

 

i did try removing half of the discs on the supertrapp, but no change. could it be my header? is it too big? not sure that would cause it to cut out, but maybe it has something to do with back pressure? i just don't have a couple hundred to take it to a shop right now.

 

thanks

 

P1030976_zps005be906.jpg

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When in doubt clean it out... Ha ha but seriously have u cleaned the carb like every last jet and passage? i would assume a sudden bog at idle would be a pilot circuit/jet problem. Also it seems u have done quite a bit of mods to your bike so I have another question have u opened up the airbox or modified it in any way? if u have opened up the airbox( holes in the side cover) I would try a simple test by covering the modified opening and see if restricting the air flow changes this problem. See I recently ran into this same problem with a customers bike and I thought it was electrical I swap every last electrical components out even the stator and pulse generator it ended up being a jetting issue. the bike would stutter and bog at any throttle position also in gear. The remedy was that the po had made too large of openings in the side cover and desnorkeld the bike and added a white brothers free flowing exhaust without up jetting so I put in two sizes larger jets and it improved drastically but the stutter was still there so I decided to block off the extra airflow from the side cover openings completely and bam problem solved the bike now runs like a raped ape no stuttering and easier start up so that is what solved the problem hope this helps

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Ah I just read your other post that's a nice airbox but I don't see any extra openings so I am stumped as well. I just figured u are having the same problem my customer was so I shared my experience with u in hopes that it will help. I learned that the air/fuel mixture is very finicky and varies from bike to bike so maybe try adding or taking away airflow from the airbox and see if u get better results

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thanks for the input. i have rebuilt the carb and blown out all passages.

 

 i guess i really need to try and post a video. i will try in the next couple of days to do it. i will take the seat off and post more picts of the airbox.

 

can a cdi go bad and the bike still run?

Edited by unclejtl

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