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Discussion Starter #1
CRF50 TB88 /HD Clutch Problems,Questions..


My Sons new Race Bike..as I got it,numbers tires have to be changed for road racing.
The Dirt Tires are very Impressive(thick) and will be for sale.
My Son currently races a XR50 but needed a serious upgrade..to this bike

The bike came with:

-Trail Bikes 88kit w big valve head upgraded to Keihin carb.
-BBR bars
-CRF 70 Suspension with HD springs(though the front end feels plush)
-Pro Circuit T-4 exhaust
-Sano chromoly footrest and Alloy pegs
-Sano tall seat
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Also Came With:
Dunlop TT92s,.......... 1 set of white wall street-and will be for sale...

I purchased the bike yesterday,(local)I quickly kick started the bike at the sellers work location but that wasn’t something I was trying to do,not get him in trouble..I know the bike and it’s original builder.
The bike started right up though it has sat..(not sure how long)

The carb metal has a lot of aluminum type corrosion-I guess that can be cleaned off with?


.........................................
I get the bike home:
I kick start it with choke on-warmed up idles..It starts but Boggs in gear Bad..
I turn it off..Fuel starts pouring out of the K&N Red Foam Filter..
I pull it off but no more fuel is coming out of carb.
I start the bike,it runs with No K&N Red Foam Filter Idles and No Bog upon riding it..no more fuel coming out of carb..

The bike had been set up,jetted with this filter ,raced over and over..What Changed?
The filter is clean,not gunked up with oil..

Why now won’t the bike run right with the filter.?
Is it possible I was just dealing with clogged jets old gas in bowl..

I installed a metal mesh Filter and the bikes a Blast to ride,no Bog. though I have not got the bike up to full speed in third..
..

The bike was raced with Race Fuel at it’s last race and is what old fuel(smells fine) is in the tank right now...I was told the bike runs fine on Pump Gas....I am not using race fuel I’m going to drain that fuel and put in high test Pump Gas.


But my biggest problem is the TB HD Semi Auto Clutch..
I can’t get the bike to not want to go when it’s in 1rst gear,no matter how low I set the idle to bike still draggs and wants to move forward..if I don’t pull it out of gear it’ll stall..
I have Read many old topics on this and have to deal with it..
But can someone direct me to How to adjust this clutch so I can try and see if I can lessen the drag..


This bike is so much fun..I was flying up and down my driveway on it laughing with giddiness ..
I have my own Honda 88 with Manual Clutch..after riding the semi auto I am torn between the two..The only thing I don’t like about the semi auto is when you downshift the bike lurches you forward..
 

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Welcome to the family!

Now to the questions, if you say the carb is clean then it is clean. I had the same issue you had and my piloet jet was not onyl clogged but also managed to striped out fully from the carb...... Gas coming out of the air filter is normally a float not being set right but if you said it was good before I would see if the pen is all good and not stuck (the thing the float pushed on to stop the flow of gas.)

I really like this video for clutch adjustment. But something something to think about is the fact that it has been raced. If you still have no luck setting the clutch up with this video there is a good chance the clutch plates are warn and need to be replaced.
 

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Discussion Starter #4
I tried the above video adjustment and was not successful ..Thanks though....My issue seems different..if I hold the shifting lever down the bike does not move like in that video..my bike drags,when it first gear it won't stop moving forward..
 

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Discussion Starter #5 (Edited)
Do 20mm Shenwey carb Jets-Pilot Fit a 20mm Keihin Carb ?


New issue. took the CRF50 TB88 outback,cleaned the gas tank out of race gas and put in new high test pump gas.

The bike started...likes to only start with choke halfway on..


The Bike starts then shuts off like it’s getting no fuel. So I checked fuel flow from the tank,that’s good,I checked fuel in the bowl..at first turning the screw on the bottom of the keihin carb did nothing then poured gas on to the motor..UGH.. Tipped the bike over and fuel comes out the overflow. I pull the carb and cleaned the jets blew them out..pilot jet I blew through,it’s tough but ‘seems ok’.....pilot is 38 main is 92

I put the Keihin 20mm Carb back on I get the bike running but it’s bogging bad when I turn the throttle..if I hold the throttle to try and get pass the bog it does not catch,the bike dies.. Swapped the Metal mech air cleaner back to the foam K & N..This make no change at all.
Checked the air mixture screw and it’s almost fully turned in,less then 1/4 out..turning it out really kills the bike it won’t even run-stalls..When I bring it fully in the bike will not bog for a few pulls of the throttle then back to bogging bad.. I have not looked at the needle clip setting because this bike ran as it’s set.. If I get the bike moving I’m getting an on and off bog then the bike dies.. Changed the plug,the plug is a dry black.. Bike had always ran it’s current carb and jets ..I know this cause I know the bike....however I was told the air mixture was set at 1 and 1/4 out so sellers lying to me. Bike sat unused for 4 months.. I can’t express how frustrated I am with this bike.. Before putting the bike away I started it and it sat running with the petcock turned off,purring...I was trying to run the gas out of the carb..the bike idled perfectly for over 5 minutes but turn that throttle BOOOOGGG!!!,.. ..that’s a lot of time I guess to run off of fuel in the bowl.. So I’m looking at my next step.



. I have a Brand New 20mm Shenwey carb.......... and jets/pilot.. This carb is set with a bigger pilot jet and main jet..(spare for other bikes) This carb looks virtually identical to the Keihin 20mm carb... Should I just slap this carb on the bike and try it..? Or should I get the stock jets for the Shenwey 20mm carb and try it like that instead? What are the stock jet sizes? Or should I try new jets in the Keihin 20mm carb,,..or try a bigger main? Do the Shenwey 20mm carb jets/pilot fit the Keihin 20mm carb? I don’t want to go stripping things..
 

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Discussion Starter #6
Watching my own vids ,maybe I have an air leak...



This is how the bike ran a few days ago,before changing the gas...
 

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Do 20mm Shenwey carb Jets-Pilot Fit a 20mm Keihin Carb ?


New issue. took the CRF50 TB88 outback,cleaned the gas tank out of race gas and put in new high test pump gas.

The bike started...likes to only start with choke halfway on..


That sounds like your pilot jet is still not clear. You said it was tough to blow through. What I do to clean pilot jets is use the smallest guitar string (I always say this because lots of guys with bikes either have, or know someone who has a guitar,) to poke it out. If it sat for all that time, and the gas smells, you can bet on some gunk in the tank, carb and jets. The gas soaking you got early on that got better on its own was from a stuck float needle, another thing that gunk can cause. The fact that you cleaned the carb once may not matter, as the tank was not flushed out at the time, and the same gunk that clogged it the first time is back for seconds. Use an in-line fuel filter, fresh gas, and plook out your pilot jet, and I'll bet you will be back in business.
 

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Discussion Starter #8
Thank you..

did this right after posting,..
Ok,got some jets out TB 20mm Kit..

Put in a New 92 main jet in the Keihin 20 mm carb...
It had a 92 main..

I put in a new 32 Pilot(it’s all I have) ..the bike had a 38 pilot..

Air screw out 1 1/4 to 2 ..

this is how it’s running....32 pilot,92 main...Should I buy a new 38 and put that in instead?


It’s really tough to read the 82 and 92 jets number as it looks the same from the TB kit..
 

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link
TBolt USA Tech Database - TBolt USA, LLC

Quick Tips For Small 4-Strokes


Please Start tuning with a Clean & Properly oiled air filter in place
Please test ride the bike , you cant jet / tune a bike sitting on the stand !


  • If it boggs or dies right off from an idle when you turn the throttle, your pilot is too lean.You Need to get the Pilot tuned in so it will come clean off an idle BEFORE moving on to other adjustments.
  • Your main adjustment is your Main Jet. Once you get your plug close with your main jet, fine tune from there.
  • When fine tuning your adjustment screws, turn them all the way in, and back out, 1 and a Half Turns, for your starting point.


TB 20mm Carb Pilot jet kit (Larger)
Part No: TBW0798
Location: 217E





20mm Pilot Jet Kit - Larger
20mm Carb Pilot Jet Kit, # 40 & 42

 

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Discussion Starter #12
I may have missed it but have you checked for air leaks?
Yes only by changing the O ring between the carb and intake.
The old one was quite flat.

Then changed the what I feel is clogged jets .
 

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Discussion Starter #13
link TBolt USA Tech Database - TBolt USA, LLC Quick Tips For Small 4-Strokes Please Start tuning with a Clean & Properly oiled air filter in place Please test ride the bike , you cant jet / tune a bike sitting on the stand ! [*]If it boggs or dies right off from an idle when you turn the throttle, your pilot is too lean.You Need to get the Pilot tuned in so it will come clean off an idle BEFORE moving on to other adjustments. [*]Your main adjustment is your Main Jet. Once you get your plug close with your main jet, fine tune from there. [*]When fine tuning your adjustment screws, turn them all the way in, and back out, 1 and a Half Turns, for your starting point. TB 20mm Carb Pilot jet kit (Larger) Part No: TBW0798 Location: 217E http://tboltusa.com/store/images/DSCI1257.JPG 20mm Pilot Jet Kit - Larger 20mm Carb Pilot Jet Kit, # 40 & 42
Thank you I shall be ordering that pilot jet kit DVD if you have #38

What I also need is a throttle cable. .. It's not a very long cable comes in the bbr bar kit .. Bbr throttle to 20 mm carb .
I was told by the seller that it's an xr80 throttle cable .
 

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Discussion Starter #14
The minimum pilot jet for the 20mm carb is the #38, if not the #40. The #32 and #35 pilot jets are too lean
Thank you ..

I know you're prob told me 1000 times . Any tips on cleaning the old pilot jet via soaking ,leaving in some type of solution ?

I'd like to try and clean out the old jets for spare parts ..
 

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Discussion Starter #16

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Discussion Starter #17
Funny thing about this bike it has its stock CDI box ..the seller told me that the bike will hit it's rev limiter and I thought huh.?.. Built motor with TB 88 cc kit but no TB rev box ..

I don't know if I should put a performance type TB CDI box in his bike or just leave it be since it's always been raced with the stock CDI box..

One thing I don't like about this bike is the stock CRF70 forks triple tree it's just seems weak to me ..I would like to upgrade the triple tree but keep the bar height ..I can't seem to find something in a simple bolt on upgrade triple tree.
 

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I had the same issue. Please read what I learned and did to fix this problem.
 
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