YFZ Central banner

Cylinder advice needed

1 reading
2.6K views 20 replies 11 participants last post by  pbsandman7  
#1 ·
Upon taking apart my motor we found a small issue. If you look in the picture you will see some scoring. My confusion is what can be done? If you run your finger over the affected area you can feel some smooth indentations. Can this be fixed or do I need to replace the cylinder?

Image

Image

Image
 
#2 ·
being that the cylinder is worn like that. that means that the nikasile coating has mostlikely been worn off which means that the cylinder itself can start to get worn faster than usual. You are probaly getting some more blow by past the cylinder rings so you are probably losing power in the engine being that there is some indentation in the cylnder. if it looks like the coating isnt flaking off then it would probably be ok if there werent any indentations. being you say that there are indentations i would suggest that you go ahead and replace the cylinder if you can afford it. it would be better than having the entire engine blow and take a chance of having more go wrong and costing more money down the road.
 
#3 ·
If you can feel indentations on the cylinder, more than likely you should have it either resleeved and/or replated. I have found that it is cheaper and quicker to just buy a new jug for a stock bore, stock stroke motor.
 
#8 ·
Big bores are great for added HP but it all comes down to how deep your pockets are. That isn't something that you want to skimp on in order to keep it reliable.

Your current cylinder looks toast so either replace it, have it recoated or bump up to a BB. It just depends on how/where you ride and what power gains you are looking for.

IMO, the order of quality for a BB goes JSR being the best, Athena 2nd and cylinder works a close 3rd.

A 98mm Standard deck JSR is 780.00. I think Athena and CW are closer to 500 and under.

A good piston, CP is the common choice for quality is going to run anywhere from 200ish to 260 depending on bore size and compression.
 
#9 ·
But both the cyl works and athena come in kits with garbage pistons, but jsr already comes with any piston you want..
 
#10 ·
I would highly recommend the JSR if you have the cheese to purchase one. Altough the 98s are in the machining process and won't be available until the end of the month. If you are interestd, I'd call JSR ASAP and put yourself on the waiting list...

From my understanding, I thought a few places sold just the cylinder for Athena and CW..? I know a majority sell a kit but I thought Kenneth at KBmotorsports was willing to separate in the past.
I could be wrong though.
 
#11 ·
Oh maybe he will, I know cylinder works stopped selling just the bb cyls alone (stupid move on their part)
 
#12 ·
take something hard like a drywall screw and try to lightly scratch the area if it scratches realy easy it is down to aluminum and needs replated. I would send it to millenium technologies they did my 125 cylinder and will be doing my rm250 cylinder this weeek they do good work.
 
#14 ·
You can go to 97mm safely..sure do that, you will notice a minor gain in power..
 
#17 ·
If they bore it alot the put the coating on thick It can crack but on yours they should be able of just strip the old coating and replate. I dont see any reson it should crack. If you are worried about it just bore it to the next size probably 2mm over. here is a little info on it Cylinder Plating Technology - Millennium Technologies
 
#18 ·
Yes 98 is the max and it can crack, 97 is safe.
I'd honestly just go stock bore but 14.5 piston. And port work
 
#21 ·
If you want to go big bore, don't cheap out and have your cylinder sleeved unless you are on an incredibly tight budget. It is much more reliable to just purchase an aftermarket cylinder.
Otherwise just have your cylinder replated and stay stock bore.