350x on dyno tonite with nitrous hit...!!

[fyi]

I was bored this evening so one of my employees and I decided to strap my 1985 350x down to the chassis dyno to see what this thing was really made of. I have no clue as to what these things were rated at from the factory back then, so I didn't really care what it made, just as long as it pulled something respectable. We made both pulls in third gear for some sort of accuracy~ I hope we guessed right on that one...

Anyway... On the second run, we shot a bit of nitrous into her to see what it would do. Man, did this thing *really* scream when it hit the engine! It picked up 5 RWHP/3 RWTQ at the flick of a switch and pulled cleanly all the way to the 8000 RPM redline. I'm running a 50/50 mix of pump fuel and 108 octane VP Racing Fuel also and the bottle was pretty much empty except for vapor.

Oh, one last thing~ This engine has Redline 15w/50 synthetic engine oil in it and even after that hard nitrous pull, the clutch performed flawlessly during the pull. We even went trail riding for an hour after the dyno flogging with absolutely no isses what-so-ever and this machine has the bone stock 20 yr. old clutch still ticking!!! I love that stuff!

BTW- Does anyone know what these engines were rated at back then? What's the factory engine RPM redline anyway??


We had a real ball and it was certainly fun to see what she's got, especially on the juice! You've got to hand it to the Japanese for building a nearly bullet-proof machine!

Photos and Dyno Graph:
http://www.3wheelerworldforums.com/attachment.php?attachmentid=15667
http://www.3wheelerworldforums.com/attachment.php?attachmentid=15666
http://www.3wheelerworldforums.com/attachment.php?attachmentid=15668

Ride on guys! :)

[prepracing]

so what kind of HP numbers did you get from the dyno :confused:

[fyi]

The dyno graph is in the links provided.

Just for clarification for those that may wonder~ this is the chassis dyno at my business and it's for automobiles, not atv's. I figured the data may be skewed, but we didn't really care, because we had no idea what it would do in the first place, we were bored and we didn't have anything to compare it to anyway. We did it more out of curiosity than anything else.

We do know however, that no matter how far the data is skewed, we still know the baseline, so as long as we keep the same tires and pull configuration/procedures the same from session to session, we'll be able to use this number as our benchmark from which we can gauge future modifications in the future. The data may be skewed by how ever much, who knows~ but at least it will be consistant and repeatable from pull to pull, which is all we really wanted to see anyway.

It was still a lot of fun and we'll hit it agin soon with a bigger shot until we find the limits of the stock parts. We'll make it a wet shot next time though so we don't melt a piston.... We want to have fun, not destroy the thing. :)

BTW- So does anyone know what these machines were rated at from the factory anyway?

[mikeboone]

I think they were about 18hp factory.

[fyi]

Do you know if they rated them at crank HP, sprocket HP or RWHP? Thanx. :)

[mikeboone]

Originally posted by fyi
Do you know if they rated them at crank HP, sprocket HP or RWHP? Thanx. :)

I think that dyno run I read was 18 at the wheels? Altitude and temperarature play good role in variations even on same bike.

What type nitrous setup did you use?

[fyi]

We just used a NX Express "Shark" n20 nozzle with a very small .021" n20 jet.

It really wasn't a "system" per 'se, just something we had lying around that we whipped up real quick to inject the n20 into this thing. :)

[mikeboone]

IC; does your shops dyno have a wideband o2 meter hooked up with computer to analyze exhaust gas?

It could provide benefit even for you 350X w/o nitrous in finding any lean/rich spots in carb circuit.

[fyi]

Yes it does and when we build this engine over the winter, we'll dial in the fueling for the new engine combination with the wideband. We debated to install the wideband in the exhaust for this n20 pull, but we decided against it for two reasons:

1. We really *didn't* want to know just how lean this thing possibly was.... :eek2: LOL!

2. We we're just to plain lazy to hook the thing up...:rolleyes: LOL!

2 1/2. The header pipe leaks anyway, so the readings would have been skewed wayyyy off the charts due to the air leak...:p

[mikeboone]

Originally posted by fyi
Yes it does and when we build this engine over the winter, we'll dial in the fueling for the new engine combination with the wideband. We debated to install the wideband in the exhaust for this n20 pull, but we decided against it for two reasons:

1. We really *didn't* want to know just how lean this thing possibly was.... :eek2: LOL!

2. We we're just to plain lazy to hook the thing up...:rolleyes: LOL!

2 1/2. The header pipe leaks anyway, so the readings would have been skewed wayyyy off the charts due to the air leak...:p

Hey! I found someone who knows what it is! lol A big bore X motor would rock! My buddies shop; Redline Motorsports does Race Porting on all 4 stroke heads; done well over 100 just for me. Good JE piston, cam, and some headwork would really wake the motor up. I take all parts down and beadblast to look new again; cylinders, heads,etc

Good luck with build and have fun!

[fyi]

Thanks Mike! :)

[wilkin250r]

They can't be 18hp. I think the 250X is only rated about 18HP, and the 350X is significantly more powerful. Back in it's day, it was known as one of the best 4-stroke motors around. It was one of the only 4-stroke motors that was actually considered "high-performance", all the other fast motors were 2-strokes.

I don't know what it was rated at, but it HAD to be more than 18HP.

[fyi]

I've been told by multiple folks on other boards that the stock HP rating at the crank is 27-28 and both of these figures came from people who read it directly from their owners/service manual. ;)

[mikeboone]

Originally posted by wilkin250r
They can't be 18hp. I think the 250X is only rated about 18HP, and the 350X is significantly more powerful. Back in it's day, it was known as one of the best 4-stroke motors around. It was one of the only 4-stroke motors that was actually considered "high-performance", all the other fast motors were 2-strokes.

I don't know what it was rated at, but it HAD to be more than 18HP.

It may be; I dont care either way. Here is RWHP from Gt Thunder website of 350x w/ Cobra slip on. Made 22 at wheels

[fyi]

That's good info, thanks! :)

[FUR92]

Wow!

[FUR92]

I've had a few 350Xs. they are still selling for a pretty good price. Except for the dents in my right shin bone I wish I still had one. They sure turn great between the trees.