Soft Sieze Issue - Trieds lots of possible fixes

[forkyleigh]

I will try to give adequate info on my scoot.  I have messaged 90gt about this a few times.  

I bought the 05 Vento Triton with low compression.  I had just planned on fixing it and selling it originally.  But a 70CC BBK was only a little more money.  So I threw a cheap ebay one on the engine.  I got the thing running.  I have always loved making cars go fast.  I was hooked on this thing in no time.

I had some soft seize issues that I had thought I had remedied on the cheap BBK.  But after some CVT changes it happened again and
wouldn't start.  It was taking forever to get My stage6 BBK so I pulled out the cheap BBK and sanded it down and unseized the rings.  This bought me a little time.  In that process I looked at the oil pump really closely.  It was set incorrectly by the prior owner.  I changed it to add more oil than the factory "line" on it.  I have verified that it is delivering oil.

I put on the Stage 6.  One hell of a difference from the cheap ebay one.  I check plugs while running it and breaking it in.  After break in, i had it seize.  So I did a short full throttle plug chop.  It seemed to lean out when heaving on the throttle.  I also had concerns of preignition.  The stock jet in the vento was an 80.  I am now up to a size 95.  It seems to be good at the 95.  I dropped the need from one notch rich, back to the middle setting.  It was way to rich at mid throttle.  That seems to help.

But, it seized with the 95 jet in it.  So I started working on helping it cool better.  I bought one of the 4 wheeler fans, as my vento had extra room for a larger fan.  It did require some trimming.  But, the fins are still much much bigger than the factory fan.  That seemed to help it cool a lot.  It seems to prolong the seizure issues.  

So I went to a heat range colder spark plug.  I think that helped some, after looking at the plug.

But, I just installed a HOCA variator on it last night.  My good did it turn the thing into a freaking ROCKET.  The stock variator was old and worn.  I tried to scuff it up, which helped but didn't last.  So I think there was some slippage.

The HOCA variator made it a little slow till about 5-7mph....  but then it takes off without the noticeable "shift."  The HOCA came with 4g rollers.  Which i think is to light for my setup (see below).  I also ordered 5g sliders, but they were on back order.  Long story short is that It brought the acceleration RPMS up significantly.  I now gets to speed literally twice as fast as it used to, but it turns higher RPM all of the time because of it.  Heavier weights should help get me where I want to be.  My top speed seems to be about the same.  I hit 62mph with the stock variator.  The HOCA had me at 60mph.  But it was a different road and much different weather.   So, with the HOCA and the colder plug it soft seized yet again.  But the plug looks AWESOME.  I didnt want to test for more speed as I don't want another seize (and i need heavier weights).  This must have happened 4 or 5 times on this cylinder/piston.  At some point it is going to give up.
 
Any thoughts?  I added more oil by adjusting the pump.  I've tried adding more oil in the tank.  I've tried lowering engine temps with the fan.  I tried a colder plug to reduce/eliminate preignition (if there was any).  I think if I go bigger on the Jet size I am going to be really really rich.  90GT suggested that I try to eliminate the oil pump.  I haven't done that yet, and plan to try that soon.  But I do not know that that is the answer.  it has to be lubed well enough.  The plug doesn't show excess oil.  It does seem to show lean either.

2005 Vento Triton GT5

70cc BBK
Hoca Variator
1500rpm Clutch Springs
1000rpm Contra Spring
Intake snorkel removed
Added two small filters to airbox
Added four vents to CVT
95 size jet on stock carb
Stock plug and Colder plug
Leo Vince ZX-R Pipe

I have used an Infared temp sensor after going for rides.  The only area that shows high temps is right by the exhaust port feeding the pipe.  That was under 300.  I pulled over and check it after a fairly high speed cruise.

Lastly, is there any coorilation in the weight of rollers vs sliders.  Should the weight be the same?  Meaning the weight I found that worked the best on rollers, will that same weight be the best for sliders?

[90GTVert]

It's probably gonna be hard to know CHT with something not mounted to the bike. They usually cool quite quickly when you let off of the throttle. Could be 50 degrees or more off by the time you stop, hop off, and get the thermo aimed.

Have you done a pressure test to look for case/intake leaks?

I've usually found that rollers and sliders work about the same on the Minarelli without needing to change weight.

[niz76]

I finally gave up on my oil pump after 3 soft seizes. Went to premix and never looked back. That's what the top dogs here do! It'd be a shame to see that Stage6 cylinder go to heck. I like 5g or 5.5 gram rollers- seems a pretty popular choice around here. Here's a tip: the GY6 stock roller weights are the same as the Hoca vari ones: 16x 13.

[forkyleigh]

The only way i can test for intake leaks is by spraying carb cleaner around the intake. Which, i have done. It shiwed no leaks. Maybe i should get me hands on one, to check the case.

Any hints on a cheap CHT sensor?

I plan to run the oil pump to itself. What premix should i try to start out? 32:1?

Thanks for the tip on weights, i figured as much!

Should i try a 100 jet? How big do they make for stock carbs?

[oldgeek]

Which stage 6 kit did you get? There were some issues with the street race iron kit for a while. The piston to cylinder clearance was too tight, and some were four cornering.

[forkyleigh]

That is the kit i have. I have the street race 70 cc cast iron. Does the company recognize the issue, or do i remove it and check it myself? Then, hone a little extra if needed.

[Corrosion]

Sept 6, 2014 8:32:50 GMT -5 oldgeek said:

Which stage 6 kit did you get? There were some issues with the street race iron kit for a while. The piston to cylinder clearance was too tight, and some were four cornering.

The first thing I do on a street race is check piston clearance. They run them to tight IMO. As tight as . .001 - .0015

I Finish hone the with a lighter grit ball hone, than the coarse version on they use. Hone half in one direction, half in the other. That de-burrs the ports nicely. Use ND 30wt oil & wash with solvent then Boiling hot soapy water rinse. When the hot water evaporates. Coat with 2-T oil, or it will rust in minutes.

The Zuma spec is .015 to .003. I like them at .003 on the Vertex pistons that Stage 6 uses.


I like the x long feeler gauges to Check the piston to wall, clearance. They give the right feel, to me.

www.amazon.com/Starrett-667-3-Thickness-Feeler-Length/dp/B00065V6R0/ref=sr_1_24?ie=UTF8&qid=1410101467&sr=8-24&keywords=Starrett-667-2-Thickness-Feeler-Length

[niz76]

Thanks for the link Corrosion. I need this.

[forkyleigh]

I am still using the stock carb. I know that this is less than ideal. I also have the snorkel removed and two uni filters in. Again, less than ideal. I was trying to make up for not having a bigger carb.

Should I stick the snorkel back in and run premix and see if that remedies the issue? I would rather have a soft seize now than after a brand new hone.

The engine turns A TON of rpm since I put the new Variator on. That shouldn't have had much of an affect on RPM. But, it only came with 4g rollers. I think I need about 5g, but the 5g sliders were on back order.

Also I pulled apart the clutch and contra spring, etc. That may have been binding before. My first "gear" was basically none existent.

[oldgeek]

Sept 8, 2014 10:20:22 GMT -5 forkyleigh said:

I am still using the stock carb. I know that this is less than ideal. I also have the snorkel removed and two uni filters in. Again, less than ideal. I was trying to make up for not having a bigger carb.

Should I stick the snorkel back in and run premix and see if that remedies the issue? I would rather have a soft seize now than after a brand new hone.

The engine turns A TON of rpm since I put the new Variator on. That shouldn't have had much of an affect on RPM. But, it only came with 4g rollers. I think I need about 5g, but the 5g sliders were on back order.

Also I pulled apart the clutch and contra spring, etc. That may have been binding before. My first "gear" was basically none existent.

I think you should pull the top end and inspect the piston, and cylinder. Then you can work from that point forward. All the oil in the world will not fix it if the piston is too tight.

If you put a uni vent in where the snorkel was, I would take it out and leave the hole open.

I have tried 4 gram sliders in mine, but they were way too light. I think I have 5 or 5.5 in it now, but I am also a heavy rider.

If you are using the stock crank, I would take it easy on the RPM's!