Atc 350x rebuild. Help and suggestions

[Shawn Powell]

So I had an appendicitis a few weeks ago. I’m fine. Due to the nature of what I do for a living I’m out for 7 weeks. Fortunately I live in California and have state disability so money wise I’m ok and had some savings. I’ve got time , money and an original 1985 piston in my 350x. Let’s get started.
I already have a 400ex carb and full exhaust I like. My plan is cam shaft from WEB and a wiseco piston.
Anyone prefer a grind? I was leaning to the more aggressive 213 grind? Feel like these bikes have plenty of bottom and could use the top to help.
Pistons? I’m gonna go with a wiseco, anyone on compression ? 10.25 or 12. Aware if I go to 12 I’ll probably be stuck on race gas with an aggressive cam. Is it a huge power difference?
Final and bigger question is bore vs Hone? My bike ran and had good compression. Less than 5% difference than oem specs. Cylinder wall looks fine. I feel like I could order a oem size wiseco and save some money ? Thoughts ? And can I hone this myself ? Anyone suggest a good tool? I’m not a machinist but I am an ok mechanic. Or pay race tech to hone it for me ? Thanks guy and wish me luck !! https://uploads.tapatalk-cdn.com/20191016/5ccc8dc7e480f77f2653a36ffdb63bf4.jpghttps://uploads.tapatalk-cdn.com/20191016/6a5effa99e1cdb7862bd67a57af692ba.jpghttps://uploads.tapatalk-cdn.com/20191016/50e1e343d189aa4f32d87045736edd63.jpg


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[Ranvier]

I recently bought a powroll 430 with cam and 12:1 piston. I haven’t had time to install it yet.

[oldskool83]

im not a fan of a heavier piston. You can get the same power and more reliablilty from a decked head porting and 5 angle valve grind. Your power is in the head more so then a domed piston. 12:1 should not require race gas. I had 13.5:1 compression in a raptor motor which only startes at 9:1 I ran 93 corn gas. I just prefere a ligth OEM piston and pulling the power out of the head...crank does not know the differance.

[jb2wheels]

When I re-ringed my 86, it already ad a 10.25:1 piston in it. Fresh Wiseco rings and a dingle-ball hone.
I also lapped the valves.

Stock cam, EX carb, XR400 head with stock muffler.
I only took it on one trip before selling so I can't speak to the longevity.

I really liked the way it ran compared to my completely stock 85. Just crisper and a little faster. No smoke. Really ran better than I expected. I should do the same mods to my 85.

I liked the stock cam because it was easier - no hardened rockers, no valve spring upgrades, etc.

No race gas because I don't want to deal with it.

The right thing to to is have a machine shop rebuild the head and check out the cylinder for you and decide what to to from there.
And put a new timing chain in it.

I'd sell you the hone for 1/2 price of new plus shipping if interested if you decide to go that route.

[Shawn Powell]

I dropped all my parts this week. Web for the cam. Went with the 213 grind. Seems most logical.
Race tech is boring my cylinder and I went with a .5 over wiseco with the 12 to 1 compression. Race tech is looking at my head, gonna make a decision on porting. Might do it depends on how much they want. Also doing a new clutch with his springs. Not expecting this have 60 horsepower just maybe upper 30s. Seems reasonable. Thanks for the info guys.


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[Shawn Powell]

im not a fan of a heavier piston. You can get the same power and more reliablilty from a decked head porting and 5 angle valve grind. Your power is in the head more so then a domed piston. 12:1 should not require race gas. I had 13.5:1 compression in a raptor motor which only startes at 9:1 I ran 93 corn gas. I just prefere a ligth OEM piston and pulling the power out of the head...crank does not know the differance.

When you ported the head did you lose bottom end or reliability? How much will it run me appox?? I’m better off on 350x funds than I anticipated. I might do both. Trying to get the best bang for my buck since I’ll hopefully never do this again.


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[oldskool83]

I put $2200 into my motor and had 60hp...it was a torque monster and reved put like a 450. Guys a 450a road it abs said holly crap. I climbed everything from a dead stop. Brad from kb5ndustries did my motor. He does services a national race team...

His head deck was 75 bucks. I added 5 new OEM valves with a 5 angle grind and his porting. I lost no reliability and it's the strongest bike I ever had. Head holds alot of hp. I was limited by carbs and if I wanted over 6php I need 39mm carbs...I'd feel power loss in 3rd on hills over 400ft. Walls at the tops were no issues with the right rubber on silt hills with 50-60% grade. My accident I july 2018 limited me from using the bike right so I left it go...now I'm good and looking for another ignore to do up for hills, flat riding is boring me.

I had so much bottom end it had to be thrown away with a stage 2 cam and springs. What it needed was a plus 6 swinger cuz plus 4.5 was still making ne wheelie up hills. trail riding it I only could use 2nd gear. I never shifted. It felt like a very healthy yz426f if you ever read one youd know what I mean, just double its torque basickly.

[yaegerb]

im not a fan of a heavier piston. You can get the same power and more reliablilty from a decked head porting and 5 angle valve grind. Your power is in the head more so then a domed piston. 12:1 should not require race gas. I had 13.5:1 compression in a raptor motor which only startes at 9:1 I ran 93 corn gas. I just prefere a ligth OEM piston and pulling the power out of the head...crank does not know the differance.

This is interesting. Can you explain why you wouldn’t run race gas in a 12:1 setup?

[Shawn Powell]

This is interesting. Can you explain why you wouldn’t run race gas in a 12:1 setup?

I’m not saying you couldn’t or maybe I won’t even need to but, wiseco when asked about this exact piston said it would be fine on fresh 91 octane. Kevin at race tech agreed and showed me some stats on 450s , 15.5 to 1 on 91 octane. Of course these are water cooled more efficient heads but none the less. I have an 11 to 1 in my 400ex runs on 91 perfect. Dunlap says his 11.5 to 1 run on pump as well. The only thing everyone has agreed on if your getting it too hot it could detonate, but I’ve never gotten my 350 that warm. If your running say 100 octane and not using it your just losing power and wasting money.


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[Shawn Powell]

I put $2200 into my motor and had 60hp...it was a torque monster and reved put like a 450. Guys a 450a road it abs said holly crap. I climbed everything from a dead stop. Brad from kb5ndustries did my motor. He does services a national race team...

His head deck was 75 bucks. I added 5 new OEM valves with a 5 angle grind and his porting. I lost no reliability and it's the strongest bike I ever had. Head holds alot of hp. I was limited by carbs and if I wanted over 6php I need 39mm carbs...I'd feel power loss in 3rd on hills over 400ft. Walls at the tops were no issues with the right rubber on silt hills with 50-60% grade. My accident I july 2018 limited me from using the bike right so I left it go...now I'm good and looking for another ignore to do up for hills, flat riding is boring me.

I had so much bottom end it had to be thrown away with a stage 2 cam and springs. What it needed was a plus 6 swinger cuz plus 4.5 was still making ne wheelie up hills. trail riding it I only could use 2nd gear. I never shifted. It felt like a very healthy yz426f if you ever read one youd know what I mean, just double its torque basickly.

Yeah that’s more than I want /need and am willing to spend. But I would like to break into the 40hp range. Make it feel like my mild 400ex. I’ll talk to my guy on Monday see what he thinks. Thanks.


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[yaegerb]

I’m not saying you couldn’t or maybe I won’t even need to but, wiseco when asked about this exact piston said it would be fine on fresh 91 octane. Kevin at race tech agreed and showed me some stats on 450s , 15.5 to 1 on 91 octane. Of course these are water cooled more efficient heads but none the less. I have an 11 to 1 in my 400ex runs on 91 perfect. Dunlap says his 11.5 to 1 run on pump as well. The only thing everyone has agreed on if your getting it too hot it could detonate, but I’ve never gotten my 350 that warm. If your running say 100 octane and not using it your just losing power and wasting money.


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I wasn’t referring to your post.

[Shawn Powell]

For anyone listening I went ahead and gave Andrew at race tech the ok to do a 5 angle valve job and port my head. Everything I’ve read and heard is you can get a lot of power from these. He’s pretty confident he can do it and has some very good documented result on similar bikes.(400ex xr600/650)
So between that a 12-1 wiseco and my 213 cam from web and my existing exhaust and 38mm carb I should hopefully be running pretty strong. Anyone have a guess on horsepower numbers? I’m hoping high 30s. Low 40s really but I just feel that’s being delusional.


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[oldskool83]

send motor over to brad...he has 4 or 5 locations in the USA.

[atc007]

I think you will be very happy with your results. There will still be some left on the table, but doubt you will ever want it.

[Shawn Powell]

I think you will be very happy with your results. There will still be some left on the table, but doubt you will ever want it.

Yeah for sure. I didn’t wanna spend 4500 bucks for a big bore with machined in valves and get all crazy for 1985 suspension to not work right. At that point I would have sold mine and bought a 450 conversion.Thanks.


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[Shawn Powell]

Wel here goes the rebuild. 12 to 1 wiseco , head done with a 5 angle valve job and some porting. Web 213 grind cam and stiffer valve springs. More pics as I progress. https://uploads.tapatalk-cdn.com/20191102/a49be226876a88d181caa37d04a62779.jpg


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[Shawn Powell]

Piston ,head and cam installed
This is going smoother than I expected. Makes me nervous. https://uploads.tapatalk-cdn.com/20191102/7e20fb3e29987b9cf32f8faa716e43c9.jpg


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[Shawn Powell]

Engine in , valves adjusted , clutch tomorrow, carb jets and button everything back together. Hopefully fire it up Monday. https://uploads.tapatalk-cdn.com/20191102/a3a2688649c8b8ca75d6cef39a6e5872.jpg


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[Shawn Powell]

Getting there. Installed new clutch today. Springs were almost 1/4” under minimum. Lost (ripped cell sort disintegrated) an o ring for the oil pump so Ordered that so maybe it doesn’t start until next week lol. But I’m a few kicks away. Going riding this week (different bike) so she’s on hold till next week. https://uploads.tapatalk-cdn.com/20191105/93e91bfa122036866263fe407c833a42.jpg


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[Shawn Powell]

https://uploads.tapatalk-cdn.com/20191116/6c237a2480391b63d14991c0cbb3f707.jpg
She lives again!! Started up pretty quick. 5th kick. Holy crap with a 12:1 piston and no decompression cable. Who talked me into that? Oh that was me. Smokes a bit as expected. Getting better even after 20 minutes or so. Having trouble idling. Didn’t mess with my carb settings at all but few like I’m too far out on pilot. I’ll play with it this weekend. Did take it for a very slow ride down the street and let me tell you about clutch springs. Wow. What a difference. Softer smoother and more pull. Get it tuned up this weekend maybe take it for a quick day ride this week. Break it in thanksgiving and should be ready to ride hard by the invasion.
Still open to any tips questions or comments. Thanks


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[BOB MARLIN]

Hey Shawn,

Going to Rasor over Thanksgiving ?.

[Bernard3rd]

Shawn,

First off feel better - if you're not already. Secondly, this looks like a fun project! I'm not sure whether you've seen this video by ATV on Demand in which they set up a 350X for Motocross.

https://www.youtube.com/watch?v=3BoVcUKNc_0&t=3s

Even if MX isn't your focus, there is some interesting 350X info in the video. It is admittedly an over the top project, but maybe there are some ideas or information which may be useful for you. The price point vs point of diminishing returns scenario is up to you to determine! And I'd agree that spending more than a 450 conversion doesn't make sense unless you're an old school purist.

[Shawn Powell]

Hey Shawn,

Going to Rasor over Thanksgiving ?.

No , unfortunately. We’re going to ocotillo wells with a different group. Plan is to be at razor for New Years possibly , the weekend after the holiday 3rd to the5th I think.


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[Shawn Powell]

I have a technical question. A long time I ago I read somewhere (I think here but I can find it ) that you had to remove your decompression cable with a bigger camshaft on the 350x. Web (who made my cam) is unaware of this. Anyone have any advice? Kinda hard to kick without it to be honest. Damn 12:1 piston. Lol. I’m thinking I imagined that post now. I’d hate to ruin my brand new valve train because I’m being a pansy and not wanting to kick this thing that hard. Also hate to wear my leg out in the bottom of a sand dune while my decompression cable collects dust in my shed. Thanks.


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[Ranvier]

I have a technical question. A long time I ago I read somewhere (I think here but I can find it ) that you had to remove your decompression cable with a bigger camshaft on the 350x.

I have never heard this. I would set the valve lash to the specs according to web then adjust the cable per usual.

[Shawn Powell]

I have never heard this. I would set the valve lash to the specs according to web then adjust the cable per usual.

Yeah I’m beginning to think I’m confusing bikes with my XR400R/400ex ‘s. I know for a fact you delete those after a bigger camshaft. I just reinstalled the cable seems to be fine (and easier to kick) I’ve always been decent at adjusting that by following the service manual specs. Thanks.


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[keister]

I love reading 350X success stories. Can't wait to see it at Invasion!!

[Shawn Powell]

Well she runs , idles ok (still not perfect but I’m hoping that clears up as the engine breaks in?) Still smokes a little Wich is to be expected. Gonna take her on a very light ride tomorrow just to break in the rings I hope. There’s a good spot Wich is pretty flat and should be empty tomorrow so I can just track back and forth in 3rd gear for a couple hours. Wish me luck. https://uploads.tapatalk-cdn.com/20191119/d44089ca4b31fe672794b4695919e633.jpg


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[350for350]

I'll bet it won't happen. you'll have to give it some juice at least once!:naughty:

[Shawn Powell]

I’m gonna put this here and in the brakes thread that got me going , but EBC still makes brake rotors for the 350x front and rear. I ordered mine today. About 110 each. I’ll post pics here when I get them. (Also new sintered tusk pads) here’s my email from EBC with part numbers https://uploads.tapatalk-cdn.com/20191121/f2af015f4ee32327546cff1678b65554.png


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[ironchop]

Nice build!

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[Shawn Powell]

I’ll leave this here but here’s some pics of my new rotors. (Pads as well and some stainless hardware ) They seem legit. Bolted up no problem and look nicer. My rear was bent , that’s how this started. Well I think my build is done. Hopefully this motor breaks in nice and quits smoking lol. Wish me luck and I’ll see you all at the invasion. https://uploads.tapatalk-cdn.com/20191123/a1804a27c2f9f52b96fa1d451f25ee58.jpghttps://uploads.tapatalk-cdn.com/20191123/a57fda228a1df93cc9c67bc96db1eb22.jpg
Old vs new https://uploads.tapatalk-cdn.com/20191123/c387bedfe3041166454e8b56e73c6ed9.jpghttps://uploads.tapatalk-cdn.com/20191123/e0afe49fd69612ef8d385e52e5505741.jpg


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[Dirtcrasher]

Nice work bud! Great to see someone invest that kind of money in a motor, I've done it a few times, lol.

Anyhow, that motor should not smoke 1 bit. I've built a few of these and there is a ring break in period, but I never had any smoke.

Are you sure you got all the rings right?? Sometimes it's easy to make a small mistake with 4 stroke rings as you have 5 gaps to stagger...

[Shawn Powell]

5 rings ? Your scaring me! There’s only three on the wiseco , 2 compression one oil. Guys at race tech say it takes about a tank of gas. It only does it while cold. Once warmed up it’s fine. Seemed to do it a lot less by the end of this weekend. I’ll keep an eye on it. I staggered the rings how wiseco said to and checked the ring gap before install.


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[yaegerb]

No there’s 5 rings and three ring slots. 2 compression, 1 oil expander and 2 oil rail rings for a total of 5. The oil rail rings sit above and below the oil expander ring in the third ring slot. If you missed putting the oil rail rings in, well, that sucks.

[Shawn Powell]

No there’s 5 rings and three ring slots. 2 compression, 1 oil expander and 2 oil rail rings for a total of 5. The oil rail rings sit above and below the oil expander ring in the third ring slot. If you missed putting the oil rail rings in, well, that sucks.

Ok, that makes more sense. Then I’m good lol. I count the oil ring assembly as one ring but I see what you mean.


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[Shawn Powell]

So I disassembled my fresh engine and I somehow managed to screw my oil ring joint stagger up. Fixed it. Started it a few times. No more oil smoke. Amazing. What a dummy I am. Also bought a new old tire from SCarr, and got some new heavier springs from race tech. Upon starting it up today I heard an exhaust leak. Figured it was from my gasket, wasn’t, there’s a break in a weld on my header. So I’m probably going to buy an HRE header and a LEXX muffler for a 450r. I’ll post pics up when I get em. https://uploads.tapatalk-cdn.com/20191216/fa2540e6a3ac82d9d94db97ce37b446e.jpg
Half of my exhaust is here and the other half is on the way. Hopefully have it next week. https://uploads.tapatalk-cdn.com/20191220/49e33c3f69891334bf9cfd48443ef34e.jpg


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[Shawn Powell]

So I finally got around to installing my new exhaust. Header is an HRE. Muffler is a 2007 450r Honda LEXX from Rocky Mountain Atv. It’s a pretty direct bolt on. I did have to purchase a gasket collar for a 2005 450r , but the muffler is a 2007 -2014. I also had to relocate / replace the rear brake master cylinder feed line from the reservoir (12$ stainless wrapped line from my local aircraft supply shop). The header comes with a second mount that bolts to the frame I wasn’t able to use because it mounts in the same spot as my nerf bars. Still feels pretty solid.
As far as performance holy heck Batman. It pulls WAY harder in the middle and bottom. This is possibly because I bought and installed a performance needle for my carb and raised the clip 1 spot up from where it was. I had a DG system and the LEXX is way quieter even without the quiet core insert. It’s a tad long and hits my six pack rack so I guess that’s going in the shed. But I’m pretty stoked. Here’s some pics.Questions or comments let me know. https://uploads.tapatalk-cdn.com/20200119/d2897ec1b747774f13d4bc2d9ce9a21f.jpghttps://uploads.tapatalk-cdn.com/20200119/da89f69454aaa9142f2670cd4365c5e1.jpghttps://uploads.tapatalk-cdn.com/20200119/e20fd2dd07936f8566a48ba9867b98d7.jpghttps://uploads.tapatalk-cdn.com/20200119/13f6d0f8e3c86d4c556f3bbe652d472f.jpg


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[oldskool83]

Your gonna burn up you rear master. Relocate it lower / or in the air box.