JustRandy

Kinda looks like a caterpillar nest. The oil rings look flat from what I can see.

Sounds good. Wonder if it has a wiseco. Can you peer into the plug hole?

Maybe because the original disintegrated? Seems like there was a place that sold aftermarket plastics. That might be your best bet if you want the original seat. Did you ever get a compression tester? Be interesting to know the compression.

I think there is a piece of metal tacked onto the flywheel that determines the timing. When it goes by the pickup coil it tells the coil to fire. So it would be that metal bit in relation to the keyway. Yeah it would be interesting to compare. If you need that plate let me know. I don't think I'd ever need it and I'm sure there's another one on the engine sitting in the woods.

I don't know anything about a 250R. What exactly is it you need? I have a 250S engine sitting in the woods rotting right now. And I have this pile of junk (Uploader rotating my pics again)

Oh jeez man. Someone should introduce that guy to locktite. Well at least you caught it before something worse happened. I was kinda waiting until you actually experienced problems before telling you this but since you have it apart I may as well tell you those coils of wire should be replaced. After 30-40 years the enamel on the wire cracks causing shorts and the problem manifests as hard starting when hot. You'd really be chasing you tail and scratching your head trying to figure out why it starts fine when cold but won't start at all when hot. At the very minimum you should at least check the resistance and compare it to the service manual, but even that wouldn't give me a lot of confidence. They don't cost much so I'd just replace them. Another thing I noticed is the 230 flywheel has more spark advance than the 250, so I put the 230 flywheel on my 250. No clue why they retarded the timing on the 250. If you have both flywheels then check it out and see if you notice the same thing.

Can't beat that!

A guy in Wisconsin demanded I send a postal money order before he'd ship a 250S engine to me. The plastics on the 250S are brittle. They changed something in the recipe. One wipeout and all your hard work will disintegrate into a 1000 pieces. Probably why that other guy who wanted $1500 had his plastics chopped.

Aw man that looks in great condition! The first pic makes it look like a quadracer. I was wondering what's up with the seat. The loose steering might be a stem bushing. I remember something about that. The shocks are really good for stock. So someone bought it for $900 then traded it to you?

Oh man, now that's cool.

Looks like I wore 0.020 off my lobes. Dang. Probably same amount off the rockers. So the 250 has a bigger intake valve, more intake duration, and same intake lift. Exhaust has more lift. Seems to me if even more lift added anything then Suzuki would have done it. That's what Vince said too. Yet every aftermarket cam has more lift.

The uploader rotated my pics. Anyway, 250S vs 230S: 250S vs 250 4x4: 230S vs 300 4x4: Keep in mind my 250S cam is worn.

The metal looks atrocious on that https://www.ebay.com/itm/393528109834?hash=item5ba01a6b0a:g:2xUAAOSwQtFhJAYA And it doesn't have the lines to set the valve timing.

Well at least they put a lot of effort into the meaningless answer which is more than I usually get. For what it's worth, the same measurement on my old 250 cam is 1.307, but that's the one I ran out of oil. Base circle is 1.108 The other lobe that doesn't seem so worn is 1.326. 33.68 = 1.326 But I wouldn't get too excited since the A cam is also 1.326. I think that cam is for the 250 4x4. The D (300 4x4) and E (230S) are less.

Thanks man. I bought 2. There are 3 left. On second thought maybe you could make money duplicating those cams lol Shipping will take a month so hope I don't forget I bought them. I got a little bit of a deal because paypal gave me $25 for buying bitcoin, so I used the $25 for the cams which reduced the price to $260 with shipping and taxes. $130 a cam ain't bad with shipping and the Trump tax included (he appointed the guy who broke the tie to give us internet sales taxes so I call it the Trump tax).

I'm not sure there would be much of a market for 250 cams which is why I want to get one before they're gone for good. I don't know why I didn't buy more when they were $100 a decade ago. Which seller did you buy from? I'm sure that's the lowest price considering your propensity for research. I just buy one and check it off my to-do list. Also need to find a spare head. If you happen to run across any let me know.

How much did they reduce the price? I need to get a spare 250 cam too just in case I forget to put oil in again lol

Holy cow did you win the lotto? lol If you put in a new valve you have to cut the seat because it won't be at the same angle as the new valve. That's the mistake I made over n over before buying the cutter.

It's amazing that there are people smart enough to do that. I always stood in awe of the LEAP software https://www.physical-lab.com/products/linearx/cae-software/leap But between using speaker software and engine software I've come to the conclusion that nothing beats real world tinkering. Software can get you in the ballpark and give understanding how the variables interconnect.

Hey that's great! Nice back tires too! With only 900 miles that's a much better deal. Wow man the carb was the first thing I wanted rid of. I can't imagine stealing a quad for that. They may as well have taken the seat too lol I bought one of those quads once and on the way to pick it up the guy said it caught fire and melted everything. By that time I was almost there so I decided to get it anyway for a reduced price. After I scavenged parts off it I made a grader out of it that tows behind my other one to smooth out my trails.

AltaVista brings back memories of when google wasn't evil lol. He has dynos posted on those pages and claims something like 5% more HP. I'd expect less gains on higher revving engines like DOHC crotch rockets. Gains should be higher in the long stroke 250s, which can't rev high enough to be choked off by small ports so nothing is really lost. Half the stuff you're talking about concerning 2-strokes I can't even conceptualize in my head to know what you mean. What the heck are boost ports? The only thing I know is the general physics and colloquial use of words wherein scavenging usually means the exhaust draws in more intake by virtue of inertia, which is a function of velocity and mass. Maybe it has some other meaning in the context of 2-strokes. After (evidently) 13 years of thinking about it I'm pretty confident that porting for velocity is the way to go in the 4-stroke arena, especially if the engine is constructed such that the piston dwells a lot at the bottom (and the reason why I like the longer intake duration of the 250S cam which takes advantage of the inertia of the air in the intake port). Basically the air is accelerated by the downstroke and, while the piston is not moving at the bottom, which is quite a long time in terms of degrees of crank rotation, the air continues to rush into the cylinder by inertia which supercharges the cylinder. What normally would be 300-400cc of air is squeezed into a 250cc cylinder (ie supercharging) because of that velocity. If the ports are too large to achieve the necessary velocity to have the inertia to supercharge the cylinder then as the piston dwells at the bottom, nothing happens and the extra duration of the 250S cam adds nothing; the intake valve may as well be closed. But the opposite will be true at high rpms since the piston moves down so fast that it can't accelerate the air fast enough to fill the cylinder because the port is too small. So tuning an engine for high rpms necessitates bigger (and shorter) ports, which makes it a dog at lower rpms because of the loss of velocity. Analogous to subwoofer ported boxes the port length and diameter determines the resonant frequency of the engine (where cylinder pressure will be highest or internal pressure of the speaker box is highest). And the dB dropoff is really sharp below the resonant frequency of the box (because the port and speaker are out of phase and cancel each other) and the same is true with engines. Scavenging in a 4-stroke would once again be a function of velocity since the exhaust gas rushing out begins drawing in the intake charge during the valve overlap. If the exhaust port is too large then nothing will happen during overlap (maybe that's why exhaust valves are always so much smaller than intake valves). Scavenging in a 2-stroke, as I understand it, is when the exhaust draws the intake charge all the way through the engine and into the exhaust pipe, then bounces off the narrowing of the expansion chamber and rushes back just in time to squeeze back in through the exhaust port before it closes which supercharges the cylinder. It's pretty cool, but only happens at a narrow band of rpms (and why they call it a power band). How the internal porting affects all that is out of my understanding except for the generalities of velocity and inertia. Tuning an engine to be a screamer is pretty fruitless in my opinion unless you're designing F1 racers. Banshees are really good at throwing dirt into the next county but kinda suck at actually winning drag races because they have no grunt to hookup the tires and get going. And that's really evident when watching souped up muscle cars getting clobbered by stock Teslas which have mountains of lowend torque. The big engines are frying the tires while the Tesla is moving down the track.

Back in 2008 somebody slapped these links on the big thread at atvconnection http://mototuneusa.com/power_news_--_think_fast.htm http://mototuneusa.com/power_news_--_homework.htm http://mototuneusa.com/power_news_--_the_2007_superbike.htm http://mototuneusa.com/power_news_--_supersonic_nozzle.htm http://mototuneusa.com/power_news_--_success_stories.htm Can't believe that site still works. Can't believe that was 13 years ago.

I've heard a lot lately about ATF as a penetrant. I'll have to try it. I've been using PB and it's hard to tell if it does anything. May as well add a can of that to my collection. Yep, I found videos on how to fix my washing machine, riding mower, push mower. Practically anything I have someone has a video on how to fix it. I don't really have an issue paying people to fix things, but it's hard to trust they will do it right. I had 2 pros look at my heatpump before fixing it myself, which was just putting a jumper from an old harddrive on the circuit board. It had something to do with the low-side pressure which the circuit diagram said was optional, so I just turned it off and that fixed it. No clue how many pros I'd have to pay before I found one who could fix it. Replacing the board didn't fix it because the new board also didn't have the jumper. Eventually one of them would have resorted to selling me a whole new unit since I'm sure none of them would have discovered a simple jumper. That was close to 10 years ago and it's still going.

Holy smokes man! Are you sure you don't have oil in the gas? lol I think I'd want to tear it down to assess the damage before sinking money into it. Someone could have ran it out of oil. You could be looking at a new head, cam, rockers, piston, rings, and bore job assuming the rod bearings are still ok. But at minimum I think it's fair to say you need new rings. That's a good idea having a spare one because I suspect you'll be spending a fortune rebuilding that smoker. Me too. Kinda makes me wonder if it ran out of oil. I burned through 4 qts of oil in mine but luckily I caught it in time before something serious happened.

I don't know much about 2-strokes but scavenging in 4-strokes is a function of velocity of air. I make my ports smaller (and uniform) to increase velocity which increases scavenging and low-midrange power (at the sacrifice of top end due to the restriction of the smaller ports). The faster I can get the air moving the more of it will fill the cylinder while the piston is doing nothing at the bottom of the stroke. It's supercharging effect similar to an expansion pipe on a 2-stroke.