Performance mod - Polished Head???
- Thread starter SuperDave
- Start date
Fabian
Well-Known Member
Nope, i never replaced any bearings. These days the engine manufacturers have mostly changed to the crowded needle roller connecting rod bearing method, which is very reliable, though it doesn't like excessively high rpm.
If you stay under 5,000 rpm, (4,800 being a nice figure for max rpm) the engine will give good reliability.
If you stay under 5,000 rpm, (4,800 being a nice figure for max rpm) the engine will give good reliability.
Wow Fabian, that's great to hear. I just replaced the needle bearing, but nothing down below. You hear of so much stuff that can really cause the domino affect on these little engines. Yeah, I'm sure that I run this engine well over 5000 RPM, but I really keep it down 85% of the time. Fabian, I know that it's much easier to keep thoughs RPM's lower with the shift kit.
Fabian, I found with a lot of time, a great needle bearing I put on. It's made in Japan, and rated at 50,000 RPM's. DA"".......Found out that the stock needle bearing is 10X14X13, so the one everybody was pointing to is 10X14X15.
Ok, put it on, and the engine really seems much tighter. It kills 95%l of the free play mounting piston to push arm.
CU, Glen
Fabian, I found with a lot of time, a great needle bearing I put on. It's made in Japan, and rated at 50,000 RPM's. DA"".......Found out that the stock needle bearing is 10X14X13, so the one everybody was pointing to is 10X14X15.
Ok, put it on, and the engine really seems much tighter. It kills 95%l of the free play mounting piston to push arm.
CU, Glen
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Fabian
Well-Known Member
I have never had a small end needle bearing fail, "ever", so i've never had to replace a failed needle bearing; in fact i've reused one small end needle bearing a total of four times which works out to around 15,000 kilometers, and that same needle bearing is in my current engine.
I'm curious as to how long it will last before it tears itself to pieces.
Having said that, i have a SickBikeParts shift kit and keep the rpms around 3,800. I don't push the engine over 4,800 rpm if i have to hold a gear longer than i want to.
Once you go over the 5,000 rpm mark, vibration seems to increase with exponential force, and it would be a logical conclusion that this mechanical stress would impact on engine longevity and reliability.
At the end of the day, it's a cheap Chinese bicycle engine, not designed to take racing engine rpms.
Sure the engine will do 7,000 rpm and higher, but for a limited time frame.
I'm curious as to how long it will last before it tears itself to pieces.
Having said that, i have a SickBikeParts shift kit and keep the rpms around 3,800. I don't push the engine over 4,800 rpm if i have to hold a gear longer than i want to.
Once you go over the 5,000 rpm mark, vibration seems to increase with exponential force, and it would be a logical conclusion that this mechanical stress would impact on engine longevity and reliability.
At the end of the day, it's a cheap Chinese bicycle engine, not designed to take racing engine rpms.
Sure the engine will do 7,000 rpm and higher, but for a limited time frame.
Yeah, Fabian I believe you may be right considering. The needle bearing I took out was like new & stock?!~ That's after 800 miles.............(So go figure?)
The only reason I felt that it was a must, was because that's all I hear is to first replace stock needle bearing?
The only reason I felt that it was a must, was because that's all I hear is to first replace stock needle bearing?
Fabian
Well-Known Member
I hear lots of things on this forum, but the results of pushing an engine too hard for what it was designed for is always going to be component failure; that and running to lean an oil/fuel ratio and an excessively lean air/fuel ratio, which cooks the piston and radiates excessive heat into the small end of the connecting rod and connecting rod bearing.
roughrider
Member
Hmmm... I am routinely running my engine at just above 5,000 rpms to drive a 27 inch tire by means of a 48 tooth sprocket. At that rpm range, it goes 19-21 mph, and I consider this my cruising mode. The vibrations are minimal. The engine and drive train sound and feel like they like this speed.
I wonder how long it will last.
I wonder how long it will last.
Yes, I would say that it might fool you as long as you keep it in that sweet range. Around here I have so much stop and go, that's hard to be able to hold a good cruising speed for any length of time. Uno, doing that does worry me a bit more, because it's harder on these bikes. It makes total sense when you weigh a bit more than average Joe.?
Whenever I pull from dead stop, I'm thinking ouch for the spokes....................(because most areas I'm doing that are on some type of incline............Anyway, I know................GET A SHIFT KIT!
Whenever I pull from dead stop, I'm thinking ouch for the spokes....................(because most areas I'm doing that are on some type of incline............Anyway, I know................GET A SHIFT KIT!
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Fabian
Well-Known Member
Like all engines, it will last as long as it doesn't make any strange rattling noises, but you can rest assured that when it does, there will be someone who advises running a smaller jet will fix the horrible clatter or that running a leaner oil/fuel ratio will fix the horrible clatter or that throwing banana peels into the engine will fix the horrible clatter, but on the other hand there will be an equal number of people who tell you to do the exact opposite, mentioning that banana peels have caused irreparable damage and a mixture of apple and orange peel should have been used instead.
roughrider
Member
Mwaa-Ha-Hah! <-- That's me, belly laughing.
But yeah, I am listening closely all the time. I did buy a spare engine, and my design mods are now in the direction of more lower end torque and a smaller rear sprocket...
Even so, my engineering sense says a lightly loaded hi revver should last a long as a hard loaded low revver. (Within rather close limits, mind you.)
