Just picked up a 2003 blaster after about an hour of riding it quit running. I pulled the head and found the piston to be broken. The connecting rod had no up and down play. I got a new jug and a wiseco I piston kit. I installed the new parts along with an oil injection delete. I premixed new fuel 32:1 and started the quad up and ran through 3 heat cycles. During these cycles after it warmed up I noticed a slight knock but it doesn't happen all the time and it seems like it happens when you rev it up and the rpms are dropping. Is a slight knock normal?
Is a slight knock normal?
- Thread starter Brapp28
- Start date
Blasters are loud engines, but it could be something worse so a couple questions first:
1: Why did you get a new cylinder? Please tell me you didnt get an ebay cylinder kit!?!? If so, attribute the knocking to that.
2: With the new cylinder did you bore the cylinder to match the piston? Or did you buy a cylinder at 66.25 and buy that same exact piston?
3: If the skirt was broken, did you split the engine cases and clean the bottom end thoroughly? Or did you just blow some air in there and call er good?
1: Why did you get a new cylinder? Please tell me you didnt get an ebay cylinder kit!?!? If so, attribute the knocking to that.
2: With the new cylinder did you bore the cylinder to match the piston? Or did you buy a cylinder at 66.25 and buy that same exact piston?
3: If the skirt was broken, did you split the engine cases and clean the bottom end thoroughly? Or did you just blow some air in there and call er good?
Got a new cylinder because it was the same price as getting the old one bored. We got a middle of the road one off amazon. The old piston ring caught on the exhaust port causing it to fail. All the parts went into the exhaust and are accounted for. The piston matches the bore and yes I drained all the oil while doing the oil injection delete and there was no metal flake.
Well u made one big mistake problem is that cylinder now u have to get a mother piston and have your stock cylinder bored to match
There is no way to know 100% that:
The piston you bought matches the bore that was on the new cylinder. Should have bought a new piston 1 size BIGGER than what was currently installed, handed both the old cylinder AND the NEW BIGGER piston to the machinist and said bore this cylinder to this piston. For the same exact price you would have had a properly fit piston. No clue why this wasnt the first option???????
You got 100% of the debris from the piston breaking.... You know whats not good for crank bearings, or needle bearings in the connecting rod? Tiny bits of metal.
If the piston doesnt shatter, again, from improper bore, who knows how long the bearings will last.
It was a brittle fracture of a small section of the piston right next to the exhaust port and they went directly out of it. I measured the bore of the cylinder and the diameter of the piston and they match. I'm asking for advice not to be belittled. I'm new to two strokes.
The new cylinder isn't good quality it's cheap bs and ur top end will blow in no time trust me save yourself the headache send ur cylinder to ken kenoconnorracing tell him u want it bored and a piston matched to the bore
Engine builders have purchased those cheap cylinders just to see if they could really be used and they found many flaws with them. They aren't very noticeable but the flaws are big. A stock cylinder bored to match a specific piston in hand is a million times more reliable than the cheap cylinders
Not trying to belittle you here bud, trying to learn you. You came here asking about a knocking question. Im telling you why I think its knocking based on what you have told us. You are new to 2 strokes, I could already tell. Now take what I have told you as criticism not me belittling you. No need to spoon feed unless thats what you want?
I dont care what you say about having all the pieces and they went right out the exhaust. You can not 100% tell me that there is not a chance that debris has got into the bearings.
Even though you order a piston from wiesco, one of the best piston manufactures, when you order a 66.25 piston, you do not get a 66.25 piston. Every piston is completely different dude to manufacturing techniques. That piston could have been 66.241, 66.233. WHO KNOWS UNTIL YOU GET THE PISTON! Will they be that far off? most likely not, but it serves my point. Running a piston in a cylinder that hasnt been bored for the exact piston its using is asking for trouble, IE: Knocking.
What is knocking? Could be a couple thing, could be piston slap, could be a rod bearing. If its piston slap, good luck running it until the skirt catches the ports yet again.
Amazon sells only knock off cylinders. Now let me tell you first hand, those are the biggest piles of junk I have ever seen. I have been in your shoes, I have bought the cylinder, and that thing last 1 ride!!! ONE! UNO! When I got it I had to spend around 10 hours with a dremel just getting it to a usable condition!! the ports were not chamfered and if you didnt do it yourself, it will snag a ring.
How did you measure said piston and cylinder? What was the piston clearance? When clearances are measured in ten thousands of an inch, things have to be right.
Average human hair is better than piston clearance. Clearance in crank bearings is even tighter. The tiniest flake from a shattered piston will destroy a bearing in short order.
You're not the first nor the last to fall for price "To good to be true"
Just remember, "You can go broke saving money"
Average human hair is better than piston clearance. Clearance in crank bearings is even tighter. The tiniest flake from a shattered piston will destroy a bearing in short order.
You're not the first nor the last to fall for price "To good to be true"
Just remember, "You can go broke saving money"
There was a write up on the eBay cylinder kit somewhere on here. Friend what I can remember the ports were not chamfered at all, and when a clean up bore was attempted, the cylinder was full of small holes in the sleeve.
Search for it on here if you want. It was a good read. It really did solve alot of the questions everyone ever had about them
Search for it on here if you want. It was a good read. It really did solve alot of the questions everyone ever had about them
Found it for you. Page 3, post #41
http://www.blasterforum.com/threads/niche-industries-top-end-kit.61580/page-3
http://www.blasterforum.com/threads/niche-industries-top-end-kit.61580/page-3
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