Xr100 Carb Woes

bnt5

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May 23, 2001
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#1
I have the dreaded throttle bogging...but first a little information to get you up to speed.

I purchased a 2001 xr100r for little to nothing from a kid due to the fact it had no compression and he didnt want to spend the money to have it fixed. I rolled it home tore apart the topend and found the timing chain had slipped and he bent both valves. To make a long story short I put 2 new valves in and new rings piston along with a bore job. This is where the carb shows up in the story to make my life miserable. During the topend I dipped the carb and rebuilt it back to perfect condition. Once the topend was complete I slapped in the carb along with a new air filter, plug and gas set my pilot screw and needle clip to factory settings and started up the bike.

She started easily and once warmed up I climbed on to start the break-in process, this is where I found I couldn't give it anything past 1/4 throttle or else she would bog, and I noticed more smoke than a four stroke should have, all signs pointing to a rich condition. I tore apart the carb again, re-dipped in Berrymans carb dip blew out passages even used carb spray this time as well, set float level and verified all jets were see-through and put her back on the bike. Same problem. Out came the carb again, changed needle clip postion to lean it out and set pilot screw setting at 1 1/2 turns out instead of the stock 2 3/8 turns. This has gone on multiple times with different settings etc..the only thing that changed is the smoke has gone mostly but the engine will not rev without bogging UNLESS the choke is engaged...when I flip the choke to the half way position the engine will rev up very high almost to WOT levels?

I really need some guidance here, this carb has been driving me nuts and I do not know how to proceed. I checked for air leaks by spraying starter fluid around carb, nothing happened. I cleaned petcock, tank and replaced fuel line. One thing I havent done is a leakdown test or compression test since my compression guage from harbor freight is a pile of doo-doo and wouldn't display a bird fart correctly.
 

motometal

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Sep 3, 2001
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#2
I think the smoke may have thrown you off course. Blue smoke = oil, black = rich. If you get better response with the choke it almost has to be lean. Does it idle ok? I would move the clip down on the needle (effectively raising the needle) and try that. Careful when you do this, easy to lose clip.
 

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