Planet Minis

arlindsay1992 · 11-27-2009, 10:00 PM

Every time I race my minibike, the clutch breaks. This is the second time and I have no doubt it would happen again if I fixed it again. The TB manual clutch is great but it can't hold up to the ported 108 motor. Once you buy the billet basket, the cast clutch hub becomes the weak link and the fingers that engage with the basket break off. So be aware of this possibility on high HP motors. This probably only affects stroked motors. So I will once again be replacing the clutch hub and also replacing my stroker crank, with a stock CRF50 crank. This should solve my clutch reliability issues. And I like to be more revvy than torquey so the 88 will be just fine for me.

This is entirely unrelated to my clutch issues but I noticed a slight area of piston to head contact. I never noticed a sound while the engine was running and it was never difficult to turn over. This is a VERY slight area of contact. I have a feeling that as long as I fix the issue that caused this whether by adding an extra base gasket or whatever, that the piston will be fine. Does anyone think differently? This motor ran strong even with the piston banging the head hundreds of times a second and the clutch hub slightly shattered. You would have never known anything was wrong except for the dragging clutch.

So what are people's opinions on the piston? I have everything else figured out with the clutch and all.

firepower354 · 11-27-2009, 10:05 PM

A second base gasket should be fine. Doesn't look like it was enough to crack the ring rand. What's the skirt to bore clearance?

Can you swap the iron center for a Honda one? They seem pretty reliable???
Horstman?

arlindsay1992 · 11-27-2009, 10:12 PM

I'll check the ring land carefully because that thought never crossed my mind. I'll make sure the ring still moves freely. I haven't checked the skirt/bore clearance, I figured I'm not going to change it so why even bother checking? I trust TB enough. I did notice a tiny bit of scuffing around the thin part of the sleeve where it drops into the cases so I'll remove some material around the deck of the case to make sure I'm not creating a hot spot on the cylinder. I know you often warn about that problem. The scuffing is very minor and nothing that I'm worried about so long as I take care of the cause now. As for the clutch, it worked fine on my Honda 50 and TB 88 for over two years but as soon as I put in the TB 108 the hub broke. Then it happened again 3 or 4 running hours after installation of a new hub. I think that with the downgrade to a stock crank the TB hub will be fine. Some may think that going back to 88 is dumb but I actually liked it better. The 108 doesn't really suit me.

firepower354 · 11-27-2009, 10:25 PM

Revvers are fun. Some times, Zing is King

HaiSpeedZ50R · 11-27-2009, 11:03 PM

Can I haz your crank?

coax · 11-27-2009, 11:50 PM

I had a TB inner hub on the clutch shatter on a TB 88cc w/ race head, so it's not just limited to the 108. I don't know this to be a wide spread problem, as I've only heard about yours. I haven't repaired that engine yet, so I don't know if it would be a continuous problem.

I also had slight valve contact on the same engine. It was a little worse than yours and never heard a thing. The engine ran like a mofo. I only took it apart when the clutch started dragging prior to the end of a race day.

Dogboy · 11-28-2009, 02:19 PM

I was planning on buying a tb117 kit and a tb billet basket and clutch, so has anyone else had this problem.

TB rate the clutch suitable for their 117cc and other brand 124cc, so have you made any enquiries to see if it is covered by their warranty?

RobbMeex · 11-28-2009, 08:00 PM

Warranty?

96Justin · 11-28-2009, 08:13 PM

dirt bike parts usually dont carry much of a warranty :P

just out of curiosity what gearing do you run?

fatcaaat · 11-28-2009, 08:16 PM

you can pickup a taky clutch kit off ebay periodically for 425 brand new. Keep your eyes peeled. Cheaper in the long run...

arlindsay1992 · 11-28-2009, 08:19 PM

TB sold me the hub and a set of plates for $27 shipped last time this happened. Gearing is 15/37. I would like the Takegawa clutch but it's very pricey even at $400. I am pretty much set on going back to 88cc.

grm · 11-28-2009, 08:52 PM

The 108 must be nice on the indoor motard track you ride. The 88 will feel like it's lacking some grunt on that track.

arlindsay1992 · 11-28-2009, 08:54 PM

I rode the 88 last year and it was plenty. The 108 is about the same on that track. Only a bit quicker.

11-27-2009, 10:00 PM	#1 (permalink)
arlindsay1992 "High Speed Record Guy" Join Date: Mar 2006 Location: Northern Virginia Posts: 4,495	My motor is out of comission Every time I race my minibike, the clutch breaks. This is the second time and I have no doubt it would happen again if I fixed it again. The TB manual clutch is great but it can't hold up to the ported 108 motor. Once you buy the billet basket, the cast clutch hub becomes the weak link and the fingers that engage with the basket break off. So be aware of this possibility on high HP motors. This probably only affects stroked motors. So I will once again be replacing the clutch hub and also replacing my stroker crank, with a stock CRF50 crank. This should solve my clutch reliability issues. And I like to be more revvy than torquey so the 88 will be just fine for me. This is entirely unrelated to my clutch issues but I noticed a slight area of piston to head contact. I never noticed a sound while the engine was running and it was never difficult to turn over. This is a VERY slight area of contact. I have a feeling that as long as I fix the issue that caused this whether by adding an extra base gasket or whatever, that the piston will be fine. Does anyone think differently? This motor ran strong even with the piston banging the head hundreds of times a second and the clutch hub slightly shattered. You would have never known anything was wrong except for the dragging clutch. So what are people's opinions on the piston? I have everything else figured out with the clutch and all.

11-27-2009, 10:05 PM	#2 (permalink)
firepower354 Advertiser Join Date: Oct 2006 Location: Flint MI Posts: 11,858 My Mood:	Re: My motor is out of comission A second base gasket should be fine. Doesn't look like it was enough to crack the ring rand. What's the skirt to bore clearance? Can you swap the iron center for a Honda one? They seem pretty reliable??? Horstman? __________________ If it has my name on it I did it;) FirepowerMinis.com 810-237-9537 M-F 9-6 Custom FPM parts and engines. Parts and service for all makes. Honda Trail Bikes parts and accessories. Piranha/Medina/Thumpstar bikes, parts, engines and accessories.

11-27-2009, 10:12 PM	#3 (permalink)
arlindsay1992 "High Speed Record Guy" Join Date: Mar 2006 Location: Northern Virginia Posts: 4,495	Re: My motor is out of comission I'll check the ring land carefully because that thought never crossed my mind. I'll make sure the ring still moves freely. I haven't checked the skirt/bore clearance, I figured I'm not going to change it so why even bother checking? I trust TB enough. I did notice a tiny bit of scuffing around the thin part of the sleeve where it drops into the cases so I'll remove some material around the deck of the case to make sure I'm not creating a hot spot on the cylinder. I know you often warn about that problem. The scuffing is very minor and nothing that I'm worried about so long as I take care of the cause now. As for the clutch, it worked fine on my Honda 50 and TB 88 for over two years but as soon as I put in the TB 108 the hub broke. Then it happened again 3 or 4 running hours after installation of a new hub. I think that with the downgrade to a stock crank the TB hub will be fine. Some may think that going back to 88 is dumb but I actually liked it better. The 108 doesn't really suit me.

11-27-2009, 10:25 PM	#4 (permalink)
firepower354 Advertiser Join Date: Oct 2006 Location: Flint MI Posts: 11,858 My Mood:	Re: My motor is out of comission Revvers are fun. Some times, Zing is King __________________ If it has my name on it I did it;) FirepowerMinis.com 810-237-9537 M-F 9-6 Custom FPM parts and engines. Parts and service for all makes. Honda Trail Bikes parts and accessories. Piranha/Medina/Thumpstar bikes, parts, engines and accessories.

11-27-2009, 11:03 PM	#5 (permalink)
HaiSpeedZ50R 1st Gear Member Join Date: Jun 2009 Location: Palm Beach Posts: 167 My Mood:	Re: My motor is out of comission Can I haz your crank?

11-27-2009, 11:50 PM	#6 (permalink)
coax 1st Gear Member Join Date: Dec 2005 Location: Colorado Posts: 193 My Mood:	Re: My motor is out of comission I had a TB inner hub on the clutch shatter on a TB 88cc w/ race head, so it's not just limited to the 108. I don't know this to be a wide spread problem, as I've only heard about yours. I haven't repaired that engine yet, so I don't know if it would be a continuous problem. I also had slight valve contact on the same engine. It was a little worse than yours and never heard a thing. The engine ran like a mofo. I only took it apart when the clutch started dragging prior to the end of a race day.

11-28-2009, 02:19 PM	#7 (permalink)
Dogboy PM Newbie Join Date: Oct 2007 Location: Australia Posts: 88 My Mood:	Re: My motor is out of comission I was planning on buying a tb117 kit and a tb billet basket and clutch, so has anyone else had this problem. TB rate the clutch suitable for their 117cc and other brand 124cc, so have you made any enquiries to see if it is covered by their warranty?

11-28-2009, 08:00 PM	#8 (permalink)
RobbMeex PM Newbie Join Date: Oct 2009 Location: Mobtown, AL Posts: 86 My Mood:	Re: My motor is out of comission Warranty?

11-28-2009, 08:13 PM	#9 (permalink)
96Justin 2nd Gear Member Join Date: Jan 2009 Location: Calgary, AB, Canada Posts: 912 My Mood:	Re: My motor is out of comission dirt bike parts usually dont carry much of a warranty :P just out of curiosity what gearing do you run?

11-28-2009, 08:16 PM	#10 (permalink)
fatcaaat 3rd Gear Member Join Date: Sep 2004 Location: Arlington, VA Posts: 3,903	Re: My motor is out of comission you can pickup a taky clutch kit off ebay periodically for 425 brand new. Keep your eyes peeled. Cheaper in the long run...

11-28-2009, 08:19 PM	#11 (permalink)
arlindsay1992 "High Speed Record Guy" Join Date: Mar 2006 Location: Northern Virginia Posts: 4,495	Re: My motor is out of comission TB sold me the hub and a set of plates for $27 shipped last time this happened. Gearing is 15/37. I would like the Takegawa clutch but it's very pricey even at $400. I am pretty much set on going back to 88cc.

11-28-2009, 08:52 PM	#12 (permalink)
grm PM Newbie Join Date: Jun 2009 Location: Ontario, Canada Posts: 80 My Mood:	Re: My motor is out of comission The 108 must be nice on the indoor motard track you ride. The 88 will feel like it's lacking some grunt on that track.

11-28-2009, 08:54 PM	#13 (permalink)
arlindsay1992 "High Speed Record Guy" Join Date: Mar 2006 Location: Northern Virginia Posts: 4,495	Re: My motor is out of comission I rode the 88 last year and it was plenty. The 108 is about the same on that track. Only a bit quicker.

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