Well, it's been a while since serious wolverine riders / modifiers had anything really good to discuss. I decided to change that.

Keep in mind.. this post is long...very very long.

Some of you may know, last September, my '95 435 Stroker FST custom Wolverine finally went down. I consider that extremely good service since it was bored/stroked even before it ever saw a single trail. Taking a stock motor, modding it out, and having it kick out twice the designed horsepower for 9 years is totally acceptable to me.

The reason for her going down was a failed valve spring. Many of you will know that there are actually 4 valve springs - 2 internal and 2 external - each valve having one of each. Now, the spring that caused the damage was the internal exhaust valve spring. This spring snapped in two. This in turn, caused a delay in timing on when the valve closed. Yep, you guessed it, upon some upper rpm riding, that lazy exhaust valve smacked the top of the piston. Result - one bent valve and one cracked piston. Well, she ran long enough to get back to the trail head. Approximately 2 minutes. I guess that's when the valve guide began to bind on the the newly bent valve stem and cause it to stick, thus loosing all compression.

Upon teardown, I checked the compression, which lead to tearing down the upper end. This showed me that the valve was bent and there was an ever so small mark in the piston from the valve face. I was truely impressed at how the cylinder looked. I've seen machines only 2 years old that looked just as bad. Anyway, pulled the cylinder and then the piston. Careful examination showed a hairline crack on the bottom side of the piston (11:1 compression ratio) under the valve pocket machined into the top side. I had to use a magnifying glass to confirm my findings.

Well, knowing this machine had given a great service life, I thought while I am sending my cylinder and head to Mickey Dunlap @ Four Stroke Tech, I might as well see if I should send him the crankshaft so he could install a new connecting rod. Well, upon inspection, the wristpin journal showed signs of wear, but again, not bad. I decided to replace it anyway. Hey, 9 years, twice the horsepower... I want this rebuild to last me the same. So, total engine teardown. As some of you know, do get the crank out.. it's all or nothing. Looks much like putting a grenade in the crankcase.. pieces everywhere. Once out, I sent the head, the cylinder, and the crank in for rebuilding.

Mickey, being a very busy man, took about 6 weeks to get my goods back to me. Upon arrival, things looked great. The inside of the head looked brand spankin new. come to find out, the inner intake valve spring was also broken and no telling just how long it had been like that. With new springs, valves, and seals, it was like new again. As for the cylinder, bored to match a 10.5:1 wiesco custom piston. Custom as Mickey has to take a Wiesco and do some machine work to get the 10.5:1 ratio I asked for. As for the crank.. the rod looked great as well. New Vesrah.

I was set. Ready to go and willing to work hard. My machine had gone down in late September, sat idle till early November when I tore her down, and now, being after christmas, I was itching to ride. Only thing stopping me was the Wolverine - a mere skeleton in the garage. Looking at me with sad eyes.. saying I want to hit the trail too. So, off to work I went.

Now, knowing that the transmission was comming apart for the crankwork, I decided that there would be no better time than the present to do the 4th and 5th gear swapouts. This project was pretty straight forward. The only problem I had was the lack of a press in order to remove / install them with. Machine shop down the road was more than happy to help out and a few hours later, whallah.. gears ready to go back in.

Once the parts are ready, the assembly goes pretty quick. I had asked Mickey about re-installing the crank into the casehalves and he said that he heats up the clutch side case half on a hotplate while at the same time, chucks the crank into the freezer. I put the crank in the night before and after the casehalf being on the hotplate for close to an hour, she was ready. The crank went right in, no complaints. I made sure that I had also heated up the oil pump drive gear is it is a press fit onto the crank as well. Since the crank was cold, this gear hot, it would slide right on as well. In doing so, the counterbalance drive gear and springs must be ready to go as well. This process went extremely smooth and once done, the rest is pretty easy.

Re-assembly went really smooth and quickly until I got to the secondary clutch nut. There is a keeper that has two flats that are bent up against the sides of the nut to lock it in place. Well, as time has progressed, I learned to take a pair of channel locks an gently apply pressure to each side of the keeper and slowly bend them up. Well, this time, I lost. The channel locks Snapped closed and in doing so jumped out away from the clutch. While doing so, they smacked into one of the standoffs for the clutch basket snapping it off cleanly at the base of the basket. ARGH. E-bay, here I come. $45 later, new/used basket in great shape.

The next holdup was one of the oil-galley banjo bolts. The bolt was fine, but the threads in the case half elected to let go. DAG NABBIT. Upon inspection, the threads went much deeper than the bolt so off to the hardware store I went. Longer bolt, just no oil passage through it. Out comes the drill. I bought two bolts knowing that hand drilling down the center of a bolt seldom goes straigh. Lucky for me, the first one went smoothly. cut it to lenght and off to the races I went.

The rest of the re-assemlby went off without a hitch. Nothing to mention. I got her all back together, added oil, and put fresh gas into the tank. Comming from an 11:1 compression ratio and 101 octane fuel to 10.5: 1 and 93 octane, I knew my jetting would be way off. I had a pretty good idea where to start, so I changed out the jets before ever firing her up. I installed my O2 sensor and Exhaust gas meter an was ready to go. Oh, did I mention the new exhaust. Yet another factor for jetting. Anyway, the first ride yielded being rich. This was my goal as I didn't want to run it lean.

I took her out to a new neighborhood.. still under construction and began the break in process. Hard acceleration 1st, 2nd, 3rd, no throttle, 2nd, 1st. Up and down trough the gears.. making sure the rings got plenty of Power/vacuum strokes. It is key that the rings be forced to both the top and bottom of the ring grooves upon breakin. After the 1st 45min to an hour.. it's over. broke in right or wrong, there is no going back. The process was tiring, but felt good as I could feel the power increase as the rings seated. Still rich, yet still a powerhouse. After 10 miles of this - approx. 45 minutes, I called it a night.

The next thing was to re-jet. Having the meter makes it easy as I can monitor it realtime. I made a pilot change as well as a Mainjet change. No since in messing with the needle just yet. Two changes later.. spot on. Using a Dial a jet means getting it spot on, then re-jetting and giving it room to work - round three. Running like a top and she sounded / performed fantastic.

My next outing was to plow the driveway a few times. On the last one, I just wondered how she would do under a load. I stood on the pegs, punched the throttle and pulled on the bars... I'll be damned.. she came up even with the plow on the front. My first thought was.. great.. how do I get it down without smacking the plow into the concrete. lol. When she came down, luckily she didn't smack. I was impressed.

This is where you think we are done. lol.. nop, un uh. There is more.

A few weeks later it was time for a maiden voyage. My atv club up in here in Michigan was having an outing and I thought no better time to ride than with others, just in case. So we were off.

The ride went fantastic.. instant power, instant throttle response, wheelying on command. merely pull on the bars and nail the throttle. UP she'd come. I was having a great time. Until then. About 25 miles into our 35 mile ride, it all went wrong. While busting a groove down a wide open trail in about 6 inches of snow, she got hot.. and I mean hot.. so hot she didn't want to idle without tapping the throttle. I let her cool down and it took a while to start her again, but she did start. Miles from the truck, I had no choice but to ride her back.. with the snow and a very particular tractionless hill, there was no way we were going to pull a dead machine home. So, here we go. Watching the O2 meter the whole time, I noticed it running more and more rich the farther we went. Finally, she didn't want to pull her own weight, much less my 220 lb frame. Stopped her on the trail and opened up the airbox.. sure enough.. the outerwear was drenched in oil. there was quite a bit of oil in the bottom of the airbox as well. Drained it and took the outerwear of and she'd run again.

The oil in the airbox was caused by blowby. I figured I had lost a head gasket in between the cylinder and the timing chain cavity. Not a total loss.. very fixable. Limped her back to the truck and loaded up.

After getting home, I had to know, so i did a quick compression check... 85psi.. not good. Off came the plastic and tank and I checked the valve clearances... just to be sure.. spot on. Well, only one thing left.. off came the head. The cylinder looked good until I rotated the crank around to move the pistion to the bottom of it's stroke. Sure enough, mid stroke was signs of aluminum galded to the cylinder wall on the intake side. Upon further inspection, there were scratches all the way around the bore. I pulled the piston and cylinder and boxed them up, knowing I was traveling for work in 2 days. When the piston came off, the wristpin journal on the crank was toast. Gald markes in the bearing surface. Mickey wouldn't be available till Monday, this was Saturday night. I wasnt' happy and didn't sleep much.

2 days later, I called Mickey and no luck.. off at the dealer show in Indianapolis. Back on Tuesday. Ack.. Called on Tuesday afternoon and had a very lengthy conversation. Ship them to me and let me take a look he says. So I did. Friday, I called back to see what he found. "I looked at the piston and instantly thought lean". He then flipped it over expecting to find heat marks from the increased exhasut temperature but didn't find any. Now to inpect the clyinder. He saw the scratches all the way around the bore. This is usually a sign of one thing. Lack of ring gap. he did a cleanup pass on the clyinder and then took one of the rings off the piston. Yep.. not enough ring gap. Since Mickey stated that parts would be ready to install when I got them, he said he'd cover it all under warranty. I was floored. Ship the crank to me as soon as you get it out and I'll get your stuff back to you as quickly as I can, he says. Well, I got it out the next week, shipped it off and a week later, I got it all back.. ready to go.

So, here I sit, parts in hand and ready to re-assemble. Wait, there is more. While i was waiting on Mickey to rework my parts, I decided to check into my rearend... yep, needs all new bearings and seals... swingarm too. Argh again.

So, here I sit, all new bearings / seals / parts and ready to reassemble. This one will take longer as I've got the rear to reabuild and while I am at it, am replacing the front wheel bearings/ seals as well as the steering stem bearings/seals. Will it end?

For those that actually got to the bottom of this post, I applaud you. Good job. For those that bailed out early, I think you missed out on a good story as well as some good information.

I am more than willing to offer insight, direction, help, or advice to anyone else with wolverine woes. There isn't much on my machine that I don't know how it works or how to repair it, so let the questions come in.

Hopefully, the majority of you are doing more riding than myself. As for you tdrango (doing 435 stroker as I sit here typing) I expect you to be riding by the middle fo next month.

Carry on.

Robert

 

Great story man, i wish i knew how to take my engine apart like u do,now a 2 stroke engine i can have apart in no time at all..anyway great story and roughly how much does the stroker kit cost

 

So if it was a 446, what is it now after overbore? or did it have an overbore left?

 

Thanks for the info! You give the rest of us hope that a stroker kit is in the future for any/all of us. I know I want one. I am just trying to get mine to run right the way it is with a FST intake and MegaMax II pipe.

 

"Some of you may know, last September, my '95 435 Stroker FST custom Wolverine finally went down. I consider that extremely good service since it was bored/stroked even before it ever saw a single trail. Taking a stock motor, modding it out, and having it kick out twice the designed horsepower for 9 years is totally acceptable to me."

That is amazing! 9 years on that big of a bore. I wonder how many years a person can get out of a stocker? Yamaha built one reliable engine.

 

I believe that's why the warrior motor made it's way to the raptor 350.

 

Good story. I am glad Mickey took care of the issues. Many builders look for the easy way out. Mickey is old school. You got to love that. He will tell you what he thinks. Now if he would build a 100hp raptor..... lol

I am thinking of having FST do some work on my kawi 700

 

you seem to know alot about atvs! Can you help me out? Maybe? lol I have a banshee and the kick start has broke away from the clutch basket or whatever that thing is that it is connected to and I need it fixed within 2 weeks before our trip! Do you have any sugestions on how to fix? Thanks!