Yes that's the same shop. Tom Carlson....TC Racing, currently builds engines for Doug Gust. For years before the 400 ex came out, the 350X engine was the top choice for 4 stroke competition engines, and the ones I have seen still racing here in Pa. are mostly all built by him. He has done some pretty wicked conversions, but is often hard to reach due to the racing schedule. I think he is closed until late October right now. A good 350X conversion is still competitve with almost any 4 stroke engine out there including modded Raptors. I have seen 350X engines all the way up to 550's converted by him..$$$$$$ but very fast. One of the most common is the 460 kit conversion, a combination stroker/bored engine(6 mm crank stroker), and 89 mm bore. To go beyond that requires case and cylinder modifications. We had a TC 363 cc that was competitve with most modern B class 4 strokes in MX all the way up to 440cc's, and beat lot's of larger engines on flat track too(490's, Raptors, etc....obviously not all but more than a few), and a partial TC conversion 423 cc (just 89 mm bore with porting carb, cam, pipe and special intake) that is still competing successfully in flat track in both open and Sportsman classes.

His shop # is 814 723 3514 ......TC Racing Engines

 

Thanks I thought he was the guy. I think I'll try to get in contact with him to build my 350x engine. I want something a little more powerful to wip some of this new stuff out today. I wouldnt want to go to big cause these 350's can be a bear to start. I would want some more power but I have to keep the airbox, cause I run in a lot of mud and dirt.

The racer I was talking too the other week told me that i can get a lot of power out of this old 350x. He said that he won the 88 championship on a 350x. He said that in 88 it was an open class and you had to race against any other know matter what the CC. He said at the 1st mile marker he was last, but at the finish he was at the lead and had won. He said that the two strokes killed him at the take off. He also told me that the crank in a 350x is most likely the strongest out there.

Unlucky

 

I am actually looking at rebuilding a 350X engine at a different shop locally(it's in the shop now).....it will be a kind of prototype to see if this can be cost effective for single cylinder air cooled applications. Don't see why not, but time (and money) will tell. I also think the cylinder, head and case of the 350X can diffuse more heat than the 400 ex,(seat of the pants evaluation..... not a measured result) so that equipped with a slightly larger oil cooler they can stand up to a few more btu's. ( The case is larger, and because it is a wet sump and six speed, finned a bit as well, and I believe there is more fin area on the 350 head and cylinder than the 400 ex.) But the 400 ex has a weight advantage due to the dry sump, the 5 speed instead of 6 speed(smaller case), and the difference in the crank. Given all the overheating problems commonly seen on YZF 426's/440's which are water cooled, I am less afraid of trying this with an air cooled design. Air flow deflectors will also be critical on the host quad.

The results will be dyno'd and the head flow tested to take a lot of guess work out of evaluating the results. The builder is actually an automotive race engine specialist who uses computor custom designed porting, piston heads, valving, and exhaust to achieve flow not stroking, but he is not a four stroke motorcyle/quad engine builder, so we will see.

 

Sounds interesting. My son has a 350x also and he raced a new suzuki 400 quad last weekend. They raced about 1/2 mile and my son got him pretty good at the start, and he started to pull on the 350x about in 4th gear. When they both got in there high gears the suzuki started to pull ahead but in the whole race he only pulled about a bike lenght on the 350x. My sons 350x is like new and the engine has little hours on it. So it was a pretty good race. I wasnt impressed with the 400 suzuki power.

The guy who owned the 400 suzuki couldnt belive he couldnt leave the 350x in the dust. It is only about 2 months old and he has a pipe and has it jetted. So I know with a little more HP I leave these guys behind.

The engine on my 350 x is stock except for a corbra header. I have had it since 1988 and the engine has never been apart. But now it is smoking andf its pretty easy to kick. Its time to put in another engine. But it still runs just fine and has good power. I bought another engine about a year ago from ebay, so its time to drop it in. I thought while I run this one, maybe I'll get the old one worked up a little?

Unlucky

 

LOL........ I know what you mean......I let my son try someone's stock z400 after he had been riding his 250X conversion which had 16" Elkas, a-arms, axle, swing arm, holeshots, modified Works ultracross rear, piped, ported and cammed, cdi, as well as having a Lectron 44/38 mounted on the aluminum intake I made for it etc. etc. That 350X was definitely faster than the stock z in a straight line, and not a valid comparison on the track given the difference in suspension, and that was the last day we rode it before I had to tear it down for valves and a bore job, meaning it was pretty tired compared to when fresh. The last mechanic who got to ride it also had a Cannibal to play with that had been mapped......his feeling was the 350X was a bit faster....not much but a bit.

My son felt a lot better about his "old" 250X/350X conversion after that. That motor was only .060" over(363 cc's) and ran easily in mx "B" with 440 ex's and r's etc. he had guys on Banshees, Raptors et all trying to follow him around the practice track and deciding that "stock" or "mostly stock" was just not the way to go...... The only other rider to hit the small triple was a Banshee, and by the third jump he had cased it and was back to the shop for repairs. Suspension rules.....power is good but suspension keeps you healthy. Our flat tracker which was set up much the same but with a bigger cam and bored to 89 mm's, (423 cc's) was about 10 - 15% faster yet

We have raced some pretty awesome 350X's at different flat tracks. You often see 4 -6 of them still out competing with the new stuff in open class, and doing well too. They are still a great old engine for a "low tech" fourstroke from 18 years ago. Got to remember most of these old race engines are in their fifth or sixth incarnation too. I wonder how many 426's or Raptor motors will still be racing in 15 years to 20 years.......

 

I doubt there will be many 400z motors out there in 10 years. What bore size do you think would be good for hill climbibing and woods trail riding. We ride mostly at a place called Tower City. 12,000 acres of woods, hills, and trails. There is some flat place to open them up but its pretty dirty. Keep in mind I will have to ride in dirt and much water. I figure a bore job, head done somewhat, and a cam. It should give me more power.

I have the swingarm extended on mine 5", and the axle is 4" over stock also. It handles pretty good with this combination. The long swingarm keeps it down on the steep hills.

 

I have a nice 85' engine for sale, all stock, email me at Live2ride300@yahoo.com

thanx

Charlie

 

An 86 mm bore is pretty reliable ...that's about 393 cc's, and there is lot's of other stuff you can do to get power besides opening up the bore too much to lose reliability. 89 mm gives you 423 cc's. Over 89 mm they used to remove the studs and fill the stud bores in the cylinders, then rebore a larger stud pattern, after reinforcing the case.

Porting and a Lectron 44/36 Taper Jet works well, but so would an FCR 39. I am used to the Lectron's and like them, but others find them a pain....I never had any real problems with them once I understood them a bit. The only thing is getting one with the right needle and flat for your air flow - they make 3 different lengths of needle and quite a few different flats for each needle, but some of them have had the flat custom ground to match the motor.. TC would be good to set you up, as he knows those engines and carbs as well as anyone.

I made a custom aluminum intake that had a taper bored exactly to match the port size and carburator outlet, and kept the original factory slope angle. That meant the intake runner was almost twice as long as stock. Whatever the reason, it made a huge difference in performance. I also ran my filters with no airbox at all, just a K&N with a sleeve which we cleaned regularily. We didn't ride much in wet conditions so it wasn't a problem without the airbox. We just used zip ties to hold things in place and support the filter. if you do the carb, filter, poweroll pipe, or even just buy their kit, it makes a strong motor.

At one flat track race on a quarter mile oval, there was a TC 350X/550, which was right up there with Dustin Wimmer's YZF426/440, Jason Dunkelberger's 330r, and Sue Parker's Banshee. Behind those four were modded Cannondales, a bunch of 350X/460's some Raptors, and a pack of r's. In the heats my 423 finished 4th(of 12) and 7th(of 14) ahead of all the 350X/460's and the Cannondales(in the second heat) and a bunch of r's and Raptors (just barely, and it might have been a weight differential as my son was only 150 lbs.) He got T-Boned during the holeshot in the main in that race so we never had a chance to run against all of them at the same time. And that was before I had a good pipe on it.

The last paragraph is just to illustrate how competitive those old 350's can still be. There was NOTHING stock on any of those bikes.

 

How much more power should be expected from a .040 over piston at 10.25:1 over the stock piston? How about a 12:1 piston? What octane gas is needed with the 12:1 compression? I've allready put a stage 3 DG exhaust on it and a 36mm VM carb(which I really don't care for). What should I do next to squeeze some more ponies out of it. I'm having a hard time just trying to not get smoked by my friend and his Preditor.

 

Hard to say. .040 is only 1 mm increase from stock . So 81 to 82 mm. You can run 38 - 40 mm carbs on these engines, but port work would help more. The 12:1 piston will certainly help, but you would probably want to mix 50/50 104 and 93 octane if you go up that high. We ran 104 even on the 14.4:1 piston we had and it was fine.......tried 109 and 114 octane as well and made no difference except that the 114 octane seemed to eat the seals in the fuel **** and it leaked badly after that.

What intake are you using? Filter? air box? Is this mounted on a trike or 250X?