PK80 Wildcat Ported from California Motorbikes is Garbage

[ImpulseRocket]

I did all that. Even corrected removing weld leftovers from the kit lol. The pz16 carb Zane sent me recently is higher quality and isn't a cheap chinese casted ones he included in his kits. This topic gives me a headache. Even looking at it lol. Second wildcat stopped working a few weeks ago. After the oil seals blew. I'm going to rip apart the entire motor eventually. Hone the cylinder. Noticed the wear was a little uneven from the rings. Nothing crucial. Perhaps just do another 100 mile run on Valvoline conventional. The motor needed new bearings for the crank. I got sick of replacing the oil seals over and over again on all his motors, because at higher rpms they all love blowing a wad into your magneto case, dirtying your magneto assembly. Oil doesnt come off cloth lightly. His crank bearings should have a metal shield at this point... But they have no shields lol.

Funny thing is, I run all of my engines with no bearing shields/seals on the crank either. Done it that way for years.. Granted none of my engines are race engines, and they all happily live at 9000rpm or less, but I have never had a problem with oil getting into my magneto cover or clutch cover from the crank case. That engine must have some pretty impressive crankcase compression.

 

[Deleted member 35519]

Funny thing is, I run all of my engines with no bearing shields/seals on the crank either. Done it that way for years.. Granted none of my engines are race engines, and they all happily live at 9000rpm or less, but I have never had a problem with oil getting into my magneto cover or clutch cover from the crank case. That engine must have some pretty impressive crankcase compression.

Yeah but have you used this engine before? It does. This engine doesn't exceed 6 hp btw.

I feel shaving a mm or so off the crank areas where the seals install and installing viton seals will do the trick. Whatever is equivelent to the inner diameter of the viton. Then some red rtv perhaps.

 

[ImpulseRocket]

Yeah but have you used this engine before? It does.

I feel shaving a mm or so off the crank areas where the seals install and installing viton seals will do the trick. Whatever is equivelent to the inner diameter of the viton. Then some red rtv perhaps.

How many PSI do you get in the crank case?

 

[Deleted member 35519]

Haven't measure PSI before. Nor is it running atm it's ripped off a bike going on another project.

 

[Nickt919]

I don't run crank bearing seals....take em out the bearing before install.

When I put a new seal in the case, I clean all oil residue off the case where the seal sits and outer edge of the seal with acetone so there's no lubricant to help the seal pop out...kind of like KY jelly vs no KY.....create some friction. After the seal is in, I use a lubed Q-tip to carefully lubricate the seal hole then lubricate the crank shaft upon install. I guess I've been lucky in this area.... I'm yet to pop a seal out.

I see some pics on FB where guys glob motoseal all over the seal and case in an attempt to glue the seal in place.

Doing things like transfer port modification and using crankcase stuffers helps up case compression. This can put added pressure on seals. If you're not racing in organized settings, it's really not necessary to do these things. The out the box modified engines today already produce wickedly dangerous speeds for a motorized bicycle.

 

[Deleted member 35519]

Correction not the case it's self in shaving but sanding down a little bit off the crank rod that retains the bearings.

 

[Deleted member 35519]

I don't run crank bearing seals....take em out the bearing before install.

When I put a new seal in the case, I clean all oil residue off the case where the seal sits and outer edge of the seal with acetone so there's no lubricant to help the seal pop out...kind of like KY jelly vs no KY.....create some friction. After the seal is in, I use a lubed Q-tip to carefully lubricate the seal hole then lubricate the crank shaft upon install. I guess I've been lucky in this area.... I'm yet to pop a seal out.

I see some pics on FB where guys glob motoseal all over the seal and case in an attempt to glue the seal in place.

Doing things like transfer port modification and using crankcase stuffers helps up case compression. This can put added pressure on seals. If you're not racing in organized settings, it's really not necessary to do these things. The out the box modified engines today already produce wickedly dangerous speeds for a motorized bicycle.

Intresting I've read about people stuffing the crank case. This may be the solution to all the problems? Because bigwigs in the game all stuff em.

 

[Deleted member 35519]

 

[Deleted member 35519]

Case Stuffing Plates

Case Stuffing Plates right and left side

dlh-performance.myshopify.com

 

[Nickt919]

Considering what we start with for an engine...quality..ect., I think stuffing is way over rated in our application. The actual stuffing gains would have to be determined on a dyno to be realized.
There's many other things on the entire bicycle/engine that can be refined to help speed.

Here's a read-only thread...it's too old to post on...but covers some case pressure ratio and stuffing...

crankcase compression ratio

Using the painstakingly accurate method of determining the crankcase compression ratio I outline at http://www.dragonfly75.com/motorbike/PCR.html I discovered that my reed valved 55cc has a ratio of 1.2 and that a meager ratio of 1.11 is existent with my 48cc piston port engine. This ratio is...

motoredbikes.com