430 kit has arrived

The last part needed to put my bike back together arrived today, 430 kit from Thumper Racing for my 99 WR 400. Parts have been trickling in including a complete clutch pack w/ springs, Hinson basket, Hot cams intake and exhaust, JD jet kit and new front fender from TT, with TT stickers of course. Personally I think the fender will make the biggest difference. The old was beat up and the scratches were disrupting the laminar airflow.

I’m going to start bolting things back together after dinner tonight and with any luck I’ll be hitting the slopes by Sunday. The engine hasn’t been touched since new except for a set of rings so it should feel a bit perkier with the bigger flow breathing through the E pipe. Then I can get back into breaking things on a regular basis and technical help posts.

I put the 449 kit in my old WR426F! The kit was "sold it" and bought a new WR450F!:cry:

I gathered up all my new parts and started bolting my engine back together. I found a lot of metal stuck inside the flywheel but it didn’t seem to have damaged the coils. I popped the new piston on the rod and then tried for 3 hours to slip the barrel over but it was impossible to get the oil ring into the cylinder. The stock cylinder has a nice taper at the bottom of the bore and the stock piston easily slides in using only your fingers to compress the rings, recommended in the manual. The 430 sleeve doesn’t leave much room for a taper at the bottom and the new rings have more tension. The barrel would slip over the first two rings but it was impossible to fit the 3 piece oil ring in by hand. The instructions that came with the rings also points this out.

Since I live in the middle of nowhere there are no bike shops and no special tools so I had to make a ring compressor. I took a chain link fence post clamp that looked close to the size, polished the inside and tapered the bottom a bit so it wouldn’t scuff the piston, and it worked like a charm. The barrel almost slipped over the piston under it’s own weight.

I was installing new Hot cams intake and exhaust cams so first I checked the valve clearance and found 4 of the 5 were on the snug side and had to order 1 shim size smaller for each.

While trying to remove the buckets I found that a small ridge had formed at the edges of the cam bearing surface and I had to carefully scrape it away with a utility knife before the bucket could be removed from its bore. I noticed that the buckets were color coded underneath and checked them with a micrometer and the different colors are different thicknesses. I thought about reorganizing the shims and buckets to get the proper clearances but the manual recommends keeping the buckets in their original bore, so I left them where they were and ordered shims.

The hotcam sprockets are slotted so you can dial them in but come preset to original factory position. I didn’t have a dial indicator so I didn’t mess with the timing and I installed a new cam chain so hopefully it’s close to spec.

I was also careful to check the piston to valve clearance, recommended with the bore kit, and especially with the new cams. The store in town had nothing really suited for the job, not even clay, so I bought the next best thing, kind of a cookie cutter solution. I spread a bit of dough in the valve cutouts after removing and eating the chocolate chips. I put a bit of oil on the head and valves to keep the dough from sticking. Then I torqued everything together and spun the crank over a few times and popped it all apart and compared the squished dough thickness to feeler gauges. There was plenty of clearance.

Everything else was straightforward. I slipped in the new Hinson basket and WB clutch pack. I had already drilled my old basket apart and installed the stock gear on the new basket. I did whip up a custom holder for the inner basket out of some junk I found and an old plate so I could torque the clutch nut. I finished buttoning everything else up and popped the engine into the frame.

I also installed a combination of my new JD jet kit and the jets that came with the bore kit. I’m sure I’ll have to play with it a bit because of the new cams and extra 30 cc’s. Even though the valve clearances were tight, they were almost in spec and I didn’t feel like waiting a month for new shims to arrive so I fired it up. It fired on the second kick but quit. I spun the idle knob a few turns, kicked again and it fired and ran smoothly.

There were only 2 problems. Oil started leaking out around my counter shaft, even though I installed a new seal. I didn’t install a new rubber O ring around the shaft so it may be that or I tore the seal during installation. I ordered both this morning.

The other problem was the gearshift was sticking. The little collar that sits on the end of the shift drum slipped off once during assembly and I’m hoping that’s all it is. I’ll have to pop off the cover and check it out today.

I finished up at 3:30 AM this morning and cleaned up the shop and called a cab (I was planning to ride home). I didn’t realize it but all cab companies shut down at 2 AM on Sundays. It a couple of miles to home and I was tired and didn’t feel like walking in –30 so I slept on a couch. An employee arrived at 7:15 and woke me up. I caught a ride home, showered and made it to work for 8:30. I’m a bit buggy now but it was well worth it to get my scoot back together again.

Dammnnn Nice Writeup...

It never ceases to amaze me what Frostbite can do with limited tools in the middle of the arctic! :cry: Great write up and pics ! :cry: Thanks again!:cry:

Thanks guys. :cry::cry::cry:

My countersahft oil seal just arrived in the mail on Thursday. I haven't touched the bike since I bolted it together. I melted my sled and just got the new barrels in on Friday so i put the sled together on Saturday, since I thought the bike would only take a few minutes for the seal and check the shifting problem.

The seal popped right in and cured the oil leak. The shifter was still jamming. I could only shift into a couple of gears which was strange. The transmission was spinning freely and shifted fine as I was assembling the engine.

I started looking for the problem and slowly this terrible feeling crept up on me that I was going to have to pull the motor and split the cases.

It was 3PM Sunday afternoon when I made the decision to yank it out. Luckily the engine had only run for a few minutes so the gaskets weren’t stuck. I split the cases, checked the tranny and it spun free and shifted fine, just like before. Then I put the cases together and could only shift 2ce. I pulled the cases apart again and found the problem.

The shift forks are mounted on solid shafts that slide back and forth with the fork, unlike some trannys where the fork slides on the shaft. The shafts slip back and forth in machined holes in the case halves. I looked in one of the holes and saw something about ¼ inch below the surface of the hole. It was a dowel that I thought I had lost and turned out to be the same size as the dowels in my sled so that’s what I replaced it with.

There are 4 holes all the same size in the case in the same area, 3 are for the shift fork shafts and the 4th is for a dowel. I guess after I tore the engine apart initially I stuck the dowel back in the case so I wouldn’t loose it, but I stuck it in the wrong hole. The dowel hole isn’t very deep so the dowel bottoms out, but the shaft holes are deep and the dowel can slip all the way in. When I was reassembling the engine I didn’t see the dowel, assumed it had gotten lost and popped in one from the sled. The transmission was flukily in a gear with the shaft all the way to one side, so the cases went together perfectly. If it was in another gear with the shaft shifted to the other side the cases wouldn’t have gone together and I would have found the problem. The transmission would shift until that shaft tried to slide into the hole and then would jam.

It was a lot of work but a simple fix and now I have a spare dowel (I bought a new one for the sled) which is always nice. I scrape all the gasket goo from the cases and bolt them back together and start on the bottom end stuff. It’s getting late and I have to work Monday morning so I start to hurry a bit. Then I hit my first problem. I had the complete clutch in and was ready to put on the side cover. All that was left was to install the shift shaft. I had left it out so I could spin the shift drum by hand to check the shifting. The shaft will not go in once the clutch basket is installed so I had to rip everything out, loctited and torqued, and stick the shaft in and reassemble everything again

The piston slipped in like a dream with my new ring compressor and I’m making up for lost time. I get the head on and torqued and then hit my second problem when I try to pop in the cams, the cam chain is too short.

It slipped a tooth on the crank sprocket and there is no way to tighten up the hanging link with both cam chain guides in place so I had to remove the head to remove the chain guide, set the cam chain properly on the bottom sprocket and bolt everything back together again.

The correct measurement for a properly seated cam chain is 7 ¾ inches measured from the top of the cylinder to the top of the cam chain if you’re holding it up at one point, like by a zip ty. If your measurement is less than that there’s a link hanging under the crank sprocket.

I button things up and pop the motor backing the frame and she’s completely ready to roll at 3 AM, so that’s 12 hours from driveable form to complete tear down to driveable again. I’m sure it’s no record time but it’s my best to date

I still haven’t ridden it since it’s still in summer form and I have to mount my winter tires and ski. That’ll be some night this week and I’ll definitely be on the slopes this weekend.

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