250R NA Build - Ultimate

[Racer x]

I would love more details of the head work.

[choneofakind]

Hehehehe, he got some head (work)

[mgentz]

@Racer x need help asap please. I started it up but had to shut it off asap when fuel started spilling from the left side of the carbs. Any reason why? You can see that there is a black plastic inlet (?) On the left side in my previous pics, however I ran the fuel line to the middle based on your recommendation. What on earth is up with the left side?

[mgentz]

The left carb failed and filled the cylinder with gas until it was coming out everywhere, including the air filter. This sux heavily as this is the first time that I have EVER used these carbs. Guess I'm calling Sudco on Mon.

[Racer x]

Is it over flowing from the vent. Check the blow level. You can use a clean hose and blow into the carb to check the needle and seat. I don't see the picture?

[mgentz]

It was coming out of the vent, the air filter...everywhere. it filled the intake tract.

The float needle must have something wrong. I will pull and clean it tonight but if not I will make sudco send me new parts because I have not used it before now.

[tubarney]

Originally Posted by mgentz

It was coming out of the vent, the air filter...everywhere. it filled the intake tract.

Something def wrong with the float mechanism. I do have my set handy if you want a photo or 2 of how it should look.

[Racer x]

Try not using the air filter . I had the same problem one time when I put the velocity stack on wrong. Covering the air bleed jets .

[mgentz]

Hmm. It is a k-0990 dual pod. Do I need to leave it off the lip just slightly?

[Racer x]

Leave it off completely and see if you have the same problem.

[mgentz]

Ok. If that does solve it, does that mean that I have to run with no filter or modify mine?

[Racer x]

If it fixes the problem you will need to do something. Did your carbs come with stacks? Notice the air holes are outside the main air intake.

[mgentz]

Yea. It came with intake bells but I do not think that those will hook up to the filter. The particular intake you speak of, is it the brass piece protruding from the front of the carbs? I may be able to leave a gap in here if so. Or I can modify a spot in the rubber to accommodate.

[Racer x]

You can't put the stacks and filters together. But notice how the brass pieces stick out under the bell? I think your filter is sucking fuel out of the air bleeds. Not really sure.i put a stack on wrong once. It covered those brass pieces. Fuel went everywhere like you describe.

[mgentz]

I just checked my filter and it goes straight through. There is nothing to block the air bleeds.

Meanwhile, I cleaned the bowl and float area. I will put the carbs back on, turn on the fuel and see what happens.

[Racer x]

Should be 14 mm of bowl height. Make sure they seal when they are upside down.

[mgentz]

Cleaned it out and re-mounted them. No leaks in 10 minutes while messing with the throttle and the air filter off. Petcock is in prime position.

[mgentz]

Still holding hours later. Something must have been in the line somewhere.

Soon....next test drive.

[mgentz]

Must have been something in the line as she holds now.

Took her out for a spin and put 35 miles on her for break in. All I can say is wow. She pulls my 15/45 gearing hard to red line in top gear. 2nd gear power wheelies might even be possible.

Now...to change the oil/filter and check for leaks. I will most likely invest in an inline filter this week as well.

[quarterliter]

any videos?

[mgentz]

not yet. I have to sign up for youtube or something. more onto the grid I go....

I have plenty of pictures and if I run her on the dyno soon I will post up the results right after. Based on the butt dyno between my new setup and the old one, 40 HP should be broken!

[quarterliter]

Hope you hit your 40 mark!

[mgentz]

me too. this has been a great learning experience and a fun journey....but it has also been a long and expensive one.

However, I will not quit until 40+ HP is broken on a NA 265cc bike.

[Racer x]

Way to go. Can't wait for the numbers.

[mgentz]

Valve stem seal blew. Time to pull the head...again...and send it back to millennium for them to fix.

Upset.

[Racer x]

What? How can that be? And how could you tell? Was it smoking

[mgentz]

Exhaust was burning oil and leaking near the head. I checked into it and there is oil sitting on the valve. This also caused it to idle poorly.

Still pissed.

[Vintage Smoke]

Don't sweat the carb over filling and leaking gas. That is actually common for any carb that sits empty for any length of time. When the float sits all the way down (empty carb) sometimes it just sticks there. Anytime I turn the fuel on on a bike where I know the carb is empty I keep a screw driver handy. Usually a few taps with a screwdriver handle "unsticks" the float and keeps it from overflowing. Chances are that when you tore the carb down and moved the float/needle around you unstuck it so now the float is operating properly.

[fast1075]

If it whacked a seal (assuming it has the correct seals, correctly installed) it will be because there is insufficient clearance between seal and the bottom of the retainer. OR the valve springs are weak or improperly set up.

Valvetrain setup is a juggling act. Especially when you are changing valve sizes. The valve stem needs to be as long as possible while still leaving enough room for shimming because the higher lift on race cams puts the retainer closer to the valve guide at max lift. This is one of the reasons some cam grinders go to a smaller base circle. It is because you have to work within the dimensional limitations of the head.

IF it killed a seal because of lack of clearance, you have two possible solutions. One would be to run cams with less gross lift. The other is to install valve guides with shorter tops if such exist.

This is not an uncommon problem when modifying valvetrains. If you are not building the head yourself, the builder should have considered and asked for the base circle for the cams you intended to run.

If the clearance is ok, the valve springs may not be controlling the valves at redline, allowing the retainer to hit the seals. Lacking a pile of depth mikes, etc, assemble using very light springs, (on the bench) install the cams, rotate to max lift and push down on the retainer to find the clearance. A dial indicator comes in handy, but you can use a stack of feeler gauges to find the clearance.

Best of luck. I would recommend a good shop, but of the two I used to deal with, One guy now builds only Pro Mod car motors, and the other works on only Harleys. Damn shame, they both build customer motors with the same care they use in their record holding motors.

[mgentz]

APE racing originally built the head. Millennium fixed it. I did not have any issues the first time after APE built it. I'm thinking it was installed incorrectly but i will have them check all angles. Thank you for all the information.

Both of these places, and every shop I used in this build, are well known.

[subxero]

perhaps the thread title should be re-named to

"250r NA Build - Ultimate pain in the ass"

[bruce71198]

Originally Posted by mgentz

me too. this has been a great learning experience and a fun journey....but it has also been a long and expensive one.

However, I will not quit until 40+ HP is broken on a NA 265cc bike.

Not to nit pick but the title of your thread states 250 NA build.

[bruce71198]

Originally Posted by mgentz

Exhaust was burning oil and leaking near the head. I checked into it and there is oil sitting on the valve. This also caused it to idle poorly.

Still pissed.

How does a leaking valve seal cause poor idle?

[mgentz]

Originally Posted by bruce71198

How does a leaking valve seal cause poor idle?

It is one of the intake valve seals and one of the exhaust that let loose. This causes oil to get sucked into the cylinder and that amount of oil doesn't burn so well.

[mgentz]

Originally Posted by bruce71198

Not to nit pick but the title of your thread states 250 NA build.

Yes Sir. No one ever said that there would not be complications along the way. Considering how many non-stock and in some cases one-off parts that I have, I'm surprised sometimes that it has gone this well.

If I would have put a bunch more clay on the wiseco pistons, I would have noticed the contact. On the flip side, one would think that a manufacturer would measure that? Especially considering that my head was not decked, the cylinder shape is still OEM.

For this issue, it could be a large variety of things. I'm not complaining, just frustrated at the time, but now I am over it. I will have the head off this weekend and packaged to go back to Millennium. No big deal.

On the whole, the setup I have now is THE BEST one so far. I am shocked at the power difference from stock or even the last one (butt dyno readings so far). No matter what the dyno says, I like this one much better.

[mgentz]

Originally Posted by subxero

perhaps the thread title should be re-named to

"250r NA Build - Ultimate pain in the ass"

No sir. My title still stands. Just the little tribulations along the way. In the end, I will have the best NA 250R build. At least on the Internet......

[mgentz]

Originally Posted by bruce71198

Not to nit pick but the title of your thread states 250 NA build.

Hey...I said I wasn't going to quit!!!

[bruce71198]

Originally Posted by mgentz

It is one of the intake valve seals and one of the exhaust that let loose. This causes oil to get sucked into the cylinder and that amount of oil doesn't burn so well.

I see, thought it was all on the exhaust side.

[cuong-nutz]

Bummer man.

[mgentz]

Originally Posted by cuong-nutz

Bummer man.

No Worries. If she was that good even after letting the seals go, I cannot wait to see what she does running at 100%.