TC 250 Hot Start Issues

[jmetteer]

OK - its official.

In a race, this bike is fucked.

Won't start in a 'dead engine start'

If it stalls, it won't re-fire on a trail.

I really don't thing I would race one of the carbed TC250s off road without a recluse core exp. I really liked the 2010 I had for MX and I did race 2 off road races with it. One race I never stalled it and one I stalled it once costing me a bunch of positions. There is just too many chances to stall in an off road event. Mine started really good for me and it could still be a pain in the ass to start once in a while.

Mine had the cam lobes chamfered by bills MC plus in Oregon and that really helped the binding and terrible kick back. The other thing that was a big help on my bike was installing the JD jet kit. It helped starting hot and cold as well as just overall running. But if the bike pop stalled and flamed out it might start right up or take 10 kicks.


Here is some video of my second and last off road race on the TC250, the dead engine start was not bad after almost dumping my bike into my friends bike just before the flag dropped. The stall later really killed me, I worked my way back up but it made life hard. Dang I miss that bike, and racing in general...

https://www.facebook.com/video.php?v=2445308502734

Later,[/media]

 

[ianbronx]

My son bought one of the run out tc250 2010 and it was a pig to start when hot and I mean 20-30 kicks and sometimes give up. I found the cam timing was out and now starts 1-2 kicks every time. It also likes a soft smooth kick. Kick it hard and it's hard to start. I also changed the bypass jet to a smaller size to get rid of the flat spot at low speed/revs hard acceleration

 

[ray_ray]

My son bought one of the run out tc250 2010 and it was a pig to start when hot and I mean 20-30 kicks and sometimes give up. I found the cam timing was out and now starts 1-2 kicks every time. It also likes a soft smooth kick. Kick it hard and it's hard to start. I also changed the bypass jet to a smaller size to get rid of the flat spot at low speed/revs hard acceleration

Please tell us more on the timing issue ...How did you find out it was out of timing and how did you correct it?

 

[ianbronx]

On comp stroke the cam gears have a smaller hole with the timing line, at TDC look through the hole to see the join of the cam cap. Lines on cams don't line up with the other cam but only to the head/cam cap join.you can also check the cam timing by seeing where the inlet valve opens and the exhaust valve closes relative to top dead center (i used a dail indator ).it should be close to even on both sides.you can mark the cam idler gear with a texta (poor mans degree wheel) to give you a rough indicator . If it is out one tooth there is a large difference . I hope this helps

 

[ray_ray]

On comp stroke the cam gears have a smaller hole with the timing line, at TDC look through the hole to see the join of the cam cap. Lines on cams don't line up with the other cam but only to the head/cam cap join.you can also check the cam timing by seeing where the inlet valve opens and the exhaust valve closes relative to top dead center (i used a dail indator ).it should be close to even on both sides.you can mark the cam idler gear with a texta (poor mans degree wheel) to give you a rough indicator . If it is out one tooth there is a large difference . I hope this helps

Thanks and I'm wanting to change my cam bearings as preventive maintenance work and will look at this when I do the work ...

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I'm not 100% sure what hole you are referring to really .., No pics?

 

[ianbronx]

The tc doesn't have cam bearings . The cams run directly in the cam tunnels like alloy ohc car heads

 

[ray_ray]

The tc doesn't have cam bearings . The cams run directly in the cam tunnels like alloy ohc car heads

Good...it must have been some earlier models I was reading about ... And I did not wanna go to Cebu City for bearings ... There is a very good bearing dealer there,.. I'm just not a city boy ....

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EDIT: I'll still be looking at the timing ... Mine both start OK but improvement might can be gained here I hope ....

 

[ScottyR]

The cam makes a big difference. If I remember correctly, the later build bikes also had a different CDI than the early production TC250s. I had a 2010 TC250 that was a super good starter yet my buddys was a POS until we changed the cam (and CDI?).

I have noticed that the early bikes have yellow paint on the rims that say Excel and the later production models have white paint.

Good luck

 

[DG Harv Serv]

Thanks and I'm wanting to change my cam bearings as preventive maintenance work and will look at this when I do the work ...

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I'm not 100% sure what hole you are referring to really .., No pics?

Its not a "Cam Bearing" but Timing Gear Bearing that can fail. If you look at the post "2010 TE 250 Timing Gear Issue" at top of 4 Stroke section there are photos showing the Cam Timing "Holes" & "Marks".

Also shows failed Bearing etc...

 

[DakarSafari]

An update.

I ordered the JD Jetting kit for the 2010 TC250 and fitted it according to their instructions (we race at sea level in Enduro conditions and in moderate temps 10C to 28C). The bike has 25 engine hours, new plug and serviced well.

The kit was easy to fit and the instructions were good.

I decided to install all the jets as described and I also added the extended billet mixture screw which I ordered at the same time.

I removed:

Needle = OBEN R (clip was 4 from top)
Pilot = #45
Main = #180
Leak = #50

(all above was as the bike was delivered by the dealer in Australia)

I installed:

Needle = RED (clip 5 from top)
Pilot = #42
Main = #185
Leak = #55

The new new mixture screw was set at 1 1/4 turns out.

I also fitted the 'thin' O Ring to the pump assembly as suggested. (Note: I hear that some TC250s were sold with a wired pump, but mine was 'stock').

Nothing else was altered - except a very slight increase in idle.

We had the chance to test the bike last saturday, prior to an Enduro Cross Country on Sunday.

In short:

a. the starting issue has gone
b. the engine is slightly more responsive and smoother in all throttle positions - it wasn't bad before, but its better now.

Note: The conditions were shocking....pouring rain and alot of mud. Starting after a stall was first or second kick with the red hot start plunger on the carb pulled fully out.

As far as I'm concerned, the issue is closed for us. Either the kit worked, or there was Divine intervention!

I hope this helps future readers.

 

[ray_ray]

Its not a "Cam Bearing" but Timing Gear Bearing that can fail. If you look at the post "2010 TE 250 Timing Gear Issue" at top of 4 Stroke section there are photos showing the Cam Timing "Holes" & "Marks".

Also shows failed Bearing etc...

Thanks! ... I'm back to Cebu City again

An update.

I ordered the JD Jetting kit for the 2010 TC250 and fitted it according to their instructions (we race at sea level in Enduro conditions and in moderate temps 10C to 28C). The bike has 25 engine hours, new plug and serviced well.

The kit was easy to fit and the instructions were good.

This JD kit is like step 1 with these machines and should bear fruit on any bike on the performance scale for sure and help with the starting ... Apparently jetting or that needle taper or what ever was bad from the factory for these bikes ...

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I have that kit installed but my bikes' starting problem was the cam ... The EX cam with that funky spring auto-decompressor gadget was faulty apparently ... Again bad from the factory apparently ... I would have to kick a dead engine 5-6 strokes with the kicker to find the compression stroke ..WTF? Do I have a hole in my piston? That was a big symptom to me and massive kickback from time to time ... I'm surprised the engine cases did not crack a few times ...

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I've got 2 of these bikes and they act totally different starting ... One likes to have the CARB throttle slide raised about 1/4" BEFORE you kick it from TDC ... This is not the kick&throttle-twist 2t method ... This method is, do the TDC stuff ... Then twist the throttle and move that throttle slide up about 1/4", pause a moment, and then do the press-down-on-the-kicker without any throttle-twist.. Really starts up the WA bike I have.. This method just works on 1 of the 2 bikes ...Hot or cold also ...

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If the factory would have put the hot-start button on the bars so it is easily accessible on each startup, it would have helped (not solved) this overall starting problem.