Topic: Wiseco pistons failing

[Jake750]

78' cb750f. My plan for this build was to have the engine bored out. Wiseco seems to be the only place you can buy big bore pistons.  I'm looking for information regarding lifespan and longevity of Wiseco forged pistons, specifically the 836cc ones. I've done some digging on the subject and have found very mixed results. Some say they are guaranteed to fail before 6k miles. Some say they last 30k+ miles as long as the engine is properly warmed up before you hit the throttle. Big bore pistons that wont last more than 10k miles isn't worth it to me.

Any info/advice/2cents regarding longevity of Wiseco pistons or other piston options would be greatly appreciated!

Thanks!

[Tracksnblades1]

The old Cast vs Forged debate.....

What are your intentions for your big bore sohc Honda?

I used Wiseco pistons with good results....

Honda 350 pistons (cast) 65mm 3rd or 4th over were popular once.
Honda 360 pistons (cast) 65.5mm never personally seen these used.
Only heard of it.

Cycle x sells cast coated pistons and wiseco big bore packages,
I think I've read.

Honda used cast pistons in most applications, including their hi rev 2 strokes.

[PeWe]

You have JE pistons too from Dynoman.
I can not see why they should not survive as long as stock pistons or even longer with correct bore clearance.

Ignition and carbs properly set and a good oil changed in time.
Warm start a few minutes and ride slowly the first 15- 20 minutes before full speed.

I blew forged RC 836 rather quick due to I missed to check 2-3 ignition. CR closer to 11 than 10.

[69cb750]

78' cb750f. My plan for this build was to have the engine bored out. Wiseco seems to be the only place you can buy big bore pistons.  I'm looking for information regarding lifespan and longevity of Wiseco forged pistons, specifically the 836cc ones. I've done some digging on the subject and have found very mixed results. Some say they are guaranteed to fail before 6k miles. Some say they last 30k+ miles as long as the engine is properly warmed up before you hit the throttle. Big bore pistons that wont last more than 10k miles isn't worth it to me.

If you want a hot rod use wiseco pistons.
If you want original reliability use Honda pistons.

[PeWe]

Stock Honda pistons will not live long with min or no warming up, full speed direct. The piston rings fell out in pieces when lifting the cylinder.
RIP my dear stock pistons my K6 had for almost 40 years ago

[Don R]

 What I'm seeing with Automotive parts in general, the majority folks that post on a subject are the ones that have had a problem. The ones that don't or haven't had a problem don't post about it much.
  If you read a thread to the end they're either inconclusive or it turns out they didn't follow instructions or took shortcuts. I'm not buying the theory that forged pistons are inferior.

[Jake750]

The old Cast vs Forged debate.....

What are your intentions for your big bore sohc Honda?

I don’t plan on using it as a track bike. I plan on riding it as often as possible though. It definitely won’t be just sitting in a showroom or anything.

[Bodi]

Totally agree about customer reviews on the internet. Look at anything and comments are mostly negative. Owners with no problems usually don't comment. There are exceptions for really crap products, but I take online gripes with much salt.
You don't know how the pistons and rings were installed, whether the bores were sized correctly, how they were broken in, how the rider treats the bike...
Wiseco has been in the piston business since 1941... I sincerely doubt they would survive until now with poor products.
I know several riders with Wiseco big bore kits and none of them has ever said the pistons caused problems. Plenty of griping about tuning their hot-rod engine with hot cam, headers, and intake mods though!
Forged pistons have a long history of good performance.

[PeWe]

No need of these forged pistons with deeper valve pockets if you have no plans of installing a hotter cam.
These are made for ported heads, cleaned up chambers and cam with higher lift + longer duration.

I know a guy that has runned Wiseco 836 in a stock K2 the last +20 years. He has just restored another engine with a new set of Wiseco 836.

He had no pinging issues to retard ignition for when I asked him. The compression must be rather high with stock head + cam.

He like the better low rpm torque.

[754]

The old Cast vs Forged debate.....

What are your intentions for your big bore sohc Honda?

I don’t plan on using it as a track bike. I plan on riding it as often as possible though. It definitely won’t be just sitting in a showroom or anything.

Does that mean the odd track day ? Or drags every weekend doing 10 runs or more, or ?

[Stev-o]

Totally agree about customer reviews on the internet. Look at anything and comments are mostly negative.
Wiseco has been in the piston business since 1941... I sincerely doubt they would survive until now with poor products.
I know several riders with Wiseco big bore kits and none of them has ever said the pistons caused problems.

+1.  I have three bikes in the garage with Wiseco forged, coated pistons.

[PeWe]

Wiseco's very thin oil rails need its man to do it right. Really easy to pinch one when assemble.

My JE 71.25mm pistons have such Wiseco rings.

[Redline it]

Totally agree about customer reviews on the internet. Look at anything and comments are mostly negative. Owners with no problems usually don't comment. There are exceptions for really crap products, but I take online gripes with much salt.
You don't know how the pistons and rings were installed, whether the bores were sized correctly, how they were broken in, how the rider treats the bike...
Wiseco has been in the piston business since 1941... I sincerely doubt they would survive until now with poor products.
I know several riders with Wiseco big bore kits and none of them has ever said the pistons caused problems. Plenty of griping about tuning their hot-rod engine with hot cam, headers, and intake mods though!
Forged pistons have a long history of good performance.

I gotta say I ride no hotrod, and one thing 4 sure nothing today can be compared to the parts of the past, I'll prove it, wiseco is only in business now because like every one else the have to use materials that are the same cheap grade of metals and their processes to compete with what we gave away purchasing slightly cheaper products saving a few dollars only. Even if a company were to forge, cast, billet, as it used to, it doesn't matter because a different breed of people will always go for the cheaper junk, they don't know any difference. Wiseco they're in the same pot. china won. By the grains of sand. These old bikes, 200000 miles were possible is one thing, but 45 yrs later it's not. These bikes require quality maintenance parts and fuels to feed them, they don't get it. That's just the way i see it.