Planet Minis

firepower354 · 10-24-2009, 07:34 PM

Rebuilt early XR75 crank (lighter) with bearings and new longer rod. Sleeved 80 jug. Easier to use the whole 80 bottom with the tighter gearing. 100 clutch bolts on. Full-flow oiling and external oil filter.

fireman_343 · 10-24-2009, 08:05 PM

Looks good.. should be a fast one! What are you putting this in? Roadrace or dirt bike?
What is the gearing differance between the 80 and 100 bottom end? I have heard the 80 trans is better for roadracing!

arlindsay1992 · 10-24-2009, 08:11 PM

What's the stock stroke?

gman · 10-24-2009, 09:20 PM

The stock XR 75 has the stroke mentioned 41.4mm

The stock XR 75 bore is 47mm
The stock XR 80 bore is 47.5mm But the top of pin to top of piston is huge suttn' like 17mm. The 80 stroke is the same as the 100 at 45mm

Hey, Terry whats the stock 75's rod lenth?
Cool kit btw! That should spin some R's lol

arlindsay1992 · 10-24-2009, 10:00 PM

So an XR75 is really the same bore stroke as a CRF70. Interesting.

firepower354 · 10-25-2009, 09:11 AM

Stock rod was 91mm, new one is 95. Gets rid of the need for a HUGE pin-to-deck piston like the Ego Overload package uses. Replacement piston is $60, instead of $200

firepower354 · 10-25-2009, 09:13 AM

I can do it with an 80 crank for 118cc (120, some call it) instead, too

firepower354 · 11-04-2009, 02:05 PM

Quote:

Originally Posted by fireman_343

Looks good.. should be a fast one! What are you putting this in? Roadrace or dirt bike?
What is the gearing differance between the 80 and 100 bottom end? I have heard the 80 trans is better for roadracing!

As usual, after some shelf time, it's up for sale. It was really just an exercise in "What if?" for the class racers on a budget. I've got a big stroker going together for my bike. Fat guys need "Oomph"

Crank, piston kit, and cylinder for $375

The 100 trans has percentage ratio drops of: 39-26-19-19 versus the 80 and it's 30-23-19-15 gear drops. The 80 also uses smaller OD main bearings (less friction) and is easier to adapt a cheap IRK to. Crank is a bunch lighter with the same stroke. And, they're cheaper

10-24-2009, 07:34 PM	#1 (permalink)
firepower354 Advertiser Join Date: Oct 2006 Location: Flint MI Posts: 10,976 My Mood:	110cc limit? 58 x 41.4 combo? Rebuilt early XR75 crank (lighter) with bearings and new longer rod. Sleeved 80 jug. Easier to use the whole 80 bottom with the tighter gearing. 100 clutch bolts on. Full-flow oiling and external oil filter. __________________ If it has my name on it I did it;) FirepowerMinis.com Custom FPM parts and engines. Parts and service for all makes. Honda Trail Bikes parts and accessories. Pitster/Piranha/Thumpstar bikes, parts, engines and accessories.

10-24-2009, 08:05 PM	#2 (permalink)
fireman_343 2nd Gear Member Join Date: Mar 2007 Location: Blacklick Ohio Posts: 358 My Mood:	Re: 110cc limit? 58 x 41.4 combo? Looks good.. should be a fast one! What are you putting this in? Roadrace or dirt bike? What is the gearing differance between the 80 and 100 bottom end? I have heard the 80 trans is better for roadracing!

10-24-2009, 08:11 PM	#3 (permalink)
arlindsay1992 "High Speed Record Guy" Join Date: Mar 2006 Location: Northern Virginia Posts: 4,369	Re: 110cc limit? 58 x 41.4 combo? What's the stock stroke?

10-24-2009, 09:20 PM	#4 (permalink)
gman 1st Gear Member Join Date: Apr 2008 Location: Pittsfield, Massachusetts Posts: 240	Re: 110cc limit? 58 x 41.4 combo? The stock XR 75 has the stroke mentioned 41.4mm The stock XR 75 bore is 47mm The stock XR 80 bore is 47.5mm But the top of pin to top of piston is huge suttn' like 17mm. The 80 stroke is the same as the 100 at 45mm Hey, Terry whats the stock 75's rod lenth? Cool kit btw! That should spin some R's lol Last edited by gman; 10-24-2009 at 09:23 PM.

10-24-2009, 10:00 PM	#5 (permalink)
arlindsay1992 "High Speed Record Guy" Join Date: Mar 2006 Location: Northern Virginia Posts: 4,369	Re: 110cc limit? 58 x 41.4 combo? So an XR75 is really the same bore stroke as a CRF70. Interesting.

10-25-2009, 09:11 AM	#6 (permalink)
firepower354 Advertiser Join Date: Oct 2006 Location: Flint MI Posts: 10,976 My Mood:	Re: 110cc limit? 58 x 41.4 combo? Stock rod was 91mm, new one is 95. Gets rid of the need for a HUGE pin-to-deck piston like the Ego Overload package uses. Replacement piston is $60, instead of $200 __________________ If it has my name on it I did it;) FirepowerMinis.com Custom FPM parts and engines. Parts and service for all makes. Honda Trail Bikes parts and accessories. Pitster/Piranha/Thumpstar bikes, parts, engines and accessories. Last edited by firepower354; 11-04-2009 at 02:06 PM.

10-25-2009, 09:13 AM	#7 (permalink)
firepower354 Advertiser Join Date: Oct 2006 Location: Flint MI Posts: 10,976 My Mood:	Re: 110cc limit? 58 x 41.4 combo? I can do it with an 80 crank for 118cc (120, some call it) instead, too __________________ If it has my name on it I did it;) FirepowerMinis.com Custom FPM parts and engines. Parts and service for all makes. Honda Trail Bikes parts and accessories. Pitster/Piranha/Thumpstar bikes, parts, engines and accessories.

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