cRanbrook build

Spare_Parts

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Nov 29, 2017
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Broke the Yamaha rings today. I was rolling pretty good and all the sudden it sounded like marbles in the engine. Took chunks out of the cylinder and put divots in the piston and head. Ran a magnet through the case and didn't pull anything out. Bearings feel smooth other the the wrist pin bearing. Wonder how much the stock cdi has to do with it. Running wise it all looked good. That's why I always keep spares. Ordered some more pistons and Namura rings along with another super charge cdi. Also ordered the zoom calipers.

At least I made it home. Said f*** itand ran it lol.
 


gary55

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Nov 27, 2012
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3,947
Broke the Yamaha rings today. I was rolling pretty good and all the sudden it sounded like marbles in the engine. Took chunks out of the cylinder and put divots in the piston and head. Ran a magnet through the case and didn't pull anything out. Bearings feel smooth other the the wrist pin bearing. Wonder how much the stock cdi has to do with it. Running wise it all looked good. That's why I always keep spares. Ordered some more pistons and Namura rings along with another super charge cdi. Also ordered the zoom calipers.

At least I made it home. Said f*** itand ran it lol.
You've had your goes with that thing. This is one of the reasons I'm a little slow to go to the steel sleeves. They don't handle failures any better, and cost a lot more to fix. It would be different if the feed back was the same as the hype of them lasting longer, but it seems most of what I'm hearing is pre mature failures. Maybe they are just getting pushed harder.
 

GreasyChris

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Jan 3, 2019
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789
Broke the Yamaha rings today. I was rolling pretty good and all the sudden it sounded like marbles in the engine. Took chunks out of the cylinder and put divots in the piston and head. Ran a magnet through the case and didn't pull anything out. Bearings feel smooth other the the wrist pin bearing. Wonder how much the stock cdi has to do with it. Running wise it all looked good. That's why I always keep spares. Ordered some more pistons and Namura rings along with another super charge cdi. Also ordered the zoom calipers.

At least I made it home. Said f*** itand ran it lol.
That's crappy, at least you made it home without walking. Knowing you, you'll have it all fixed up and probably running faster than you were.
 

FNTPuck

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Jul 2, 2018
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You've had your goes with that thing. This is one of the reasons I'm a little slow to go to the steel sleeves. They don't handle failures any better, and cost a lot more to fix. It would be different if the feed back was the same as the hype of them lasting longer, but it seems most of what I'm hearing is pre mature failures. Maybe they are just getting pushed harder.
I run 32:1 oil instead of the 40:1 most run on the normal jugs, and my rod end has malossi circlips. The steel sleeve doesn't expand as fast as the aluminum piston so you really need to warm the bike up gently before flogging it. When I tore my top end down at ~100 miles to upgrade the circlips and further port it my piston was already showing scuff marks on the side from beating on it as soon as it starts. None of my stock chrome jugs did that even with many times more miles. Now I take it easy for the first few blocks until I feel its warmed up, and after pulling it to skirt the piston not too long ago I noticed it hasn't gotten any worse at all since I started doing that.

I can imagine someone using 40:1 or 50:1 and just hopping on and going straight to WOT damaging one pretty easily.
 

Spare_Parts

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Nov 29, 2017
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Like I've said before I beat on my sh*t lol. This is the odd ball bgf cylinder and it's cast iron. The rings may have been damaged as they were nos and cheap. The cylinder maybe useable after cleaning up the transfers. I'm a bad example to look at for the cylinders. The exhaust port blowing out on the g5 was my fault.

Anyway, going to try the jug with the giant exhaust port again. Jb welded the hole in the other cylinder so I might try that out.
 

Spare_Parts

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Nov 29, 2017
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Bikes back together and running great. Used the big port cylinder. Power band is much higher than it was. Still has decent bottom end but it's not great. Might be faster this time around.

So the cylinder needed a light honing. Fine. Pull out my Amazon hone and the stones fell out. Wtf lol. Threw it in the trash. Still needs honing. Wet sanded it with 400 grit. Good to go! Piston had scuff marks on each side of the boost port. 800 grit this time. Also added some dimples in that area. Have seen some Wiseco pistons that have them in high load areas. Also widened the boost port and reshaped the transfers to fire up a little more. Added a notch to the boost port as well. Seems to help a lot on top end.

Have to lean it out some. Up jetted just to be safe. Has a 52 and 110 now. Going to a 50 108.
 

Spare_Parts

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Nov 29, 2017
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Been having heat issues lately. Went a little richer and a b8hs plug in an attempt to run cooler. Didn't seem to help any. Decided to go back to a bigger id stinger, this time 18.5mm. It helped. Think the other part of the problem is the timing. Still have the stock cdi on the bike. Waiting on the super charged cdi or the PW80 cdi to come in.

Swapped the front caliper for a Zoom caliper. Don't need one on the back. First time I hit the brakes the rear tire locked lol. Can't wait to see how it works once the pads are seated.


 

GreasyChris

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Jan 3, 2019
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789
Im really happy with those calipers. They work really well and are super affordable.
Hopefully the new CDI will cure your heat issue. The extra hot July isn't helping any either.
 
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