Question for the gurus on intake manifold issues!

mountain80 · May 7, 2014

Heres the pics of the dent. Oh and another piece of info, the outlet on the exhaust is just a piece of ss pipe clamped over the oem sbp pipe to divert a bit of exhaust, also the fiberglass packing that came in the pipe was shot so it hass ss scrubpads for packing, hopefully the more info I give the better to be helped.

The pics show the size and shape of the dent!

Theon · May 7, 2014

The dent maybe able to be fixed by pressurizing the pipe?
Never tried it my self but have heard to it being done.

sub66 · May 7, 2014

leave the dent alone. i ran over my sbp yesterday 3 times. its 20 percent dented and so far cant tell the difference besides less expansion pull but thats obvious.

i want to help but im finding it difficult cause all u said was lost rpms??? so does it run ok elsewhere? did u try stock head/ ignition.

sub66 · May 7, 2014

says jetting/ a air leak or spark issues to me.

first move pipe longer to get more backpressure. say 3 inches and holler back. i had trouble w my sbp pipe length doing what u said. i remember now. longer pipe.....

Davezilla · May 7, 2014

Where's that dent located? is it more on the belly of the pipe? I can't tell from the picture but it does look like it's in an area where it wouldn't effect it that much, if it's on the baffle cone, that's where it would have a very noticeable effect so let's rule that out for now. The way to fix a dent like that would be to pressurize the pipe then use a propane or mapp torch and carefully heat it to cherry red up to orange hot until you see the dent start to come up, working from the outter edges inward then you can eather pull the heat as it comes back to level or release the pressure. Just gotta pay attention to how much pressure and how much heat is applied or... https://www.youtube.com/watch?v=8-7_AXsqujU ... This is a much safer method where the pipe is pressurized but not connected to the supply line... https://www.youtube.com/watch?v=2XpEhDAmleo his video file got corrupted but you can definitely see the method. the trick is to pressurize up to about 70psi (I'd go lower like try 50psi as these pipes are thinner metal) and heat the outside of the dent working your way in... But let's leave this alone for now.

I'm still suspecting something about the new manifold more than anything else since that's all that's been changed, what about the inside diameter of the new manifold? If it's smaller than the old one or there's a lip at the manifold/carb connection it could become restrictive as the airflow increases thru that point.

sub66 · May 7, 2014

took the dented pipe out riding and its no worse for wear. maybe its better. newish top end so its harder to say for sure. its great really anyway.... the dents cant tell.

Davezilla · May 7, 2014

It all depends on where the dents are... in some areas you'll never know the difference, but in other places it'll throw off the whole performance curve...

sub66 · May 7, 2014

i had to detune my pipe anyway. with my reed cylinder. it pules a 36t from idle to redline while accelerating up hills that all vehicles have trouble with. with a sbp pipe. he will be ok i think.

sub66 · May 7, 2014

i think we were discusing the dent in the picture posted still???? i think he will be ok....

Davezilla · May 7, 2014

It's already been discussed, he'll be ok... What I really want to see is a pic or video of this super bad bike you got that's so much better and quicker than everyone else's. otherwise, I'm not impressed.

sub66 · May 7, 2014

hmm well good luck w ur engine too friend. it doesnt hit top speed in 100 feet. i had one like that a whila ago and it was peaky and aggressive. i would like to see some sweet videos too lmao

mountain80 · May 8, 2014

Anyways I was able to build the carb adapter to go back to the oem manifold and have read all the posts up to date, I did shorten the pipe up last year as it had to loop up then down as I have very little room, came outta the exhaust, swooped up then down then forward so I shortened it etc. If this could be a problem I can try and build a piece to lengthen it before the expansion chamber. I took a pic of the pipe just to show where the dent is it is on the rh side of the expansion chamber. I also took a pic of the new manifold, it is a full 16mm through and blended to the port I pie cut and tacked the pipe the then went in and blended everything smoothly I cannot see any restriction except one thread on the barb and I can trim that easuly. I am prepping a new cylinder and piston the other one was scratched lightly all around strange I run 30:1. heres pics for the discussion. last pic is up to the lamp to show the bore.

sub66 · May 8, 2014

i got it.... lol that exhaust mount is too nice sir!!!

you should get the one everybody else has then offer all the measurements of the best one pictured. meanwhile a team will decide wich exhaust hanger should be used regardless of what you wanted or needed.
looks nice what is it?

mountain80 · May 8, 2014

It is a ss band clamp then I spun out an aluminum spacer that bolts to where normally a kickstand bolts to a small triangular plate on a bike. Tapped it with same threads as band clamp bolt ummm maybe 1/4-28 UNF.

Davezilla · May 8, 2014

That is a sweet looking mount setup you got there... the best ones are always home made... Keep us posted on how it works...

BTW... I got some sweet pics... and a not so sweet vid of me breaking in the new engine in the driveway before I put my new pipe on it, the old one broke off at the bracket weld so I made a new one that looks and sounds way better... test ride tomorrow. I'm also still running that junk of a speed carb on it (new carb on the way too) but it still sounds nice... I put my pics in a new post here... it's a highly modified KTM 50 pipe that I decided not to use until my pipe broke earlier today... lol. It also has a dent in it but it's also in a non critical area so I didn't do much more than just hammering it out as well as I could when it was cut in half. http://motorbicycling.com/showthread.php?t=55153

rogergendron1 · May 12, 2014

I am running a 16mm carb and a 16mm ID bore intake also yhough my intake is a long one but my bike reaxhes 9,000 rpms in a friggin flash .....

I think you may have a air filter restriction ... When i was using the sbp high flow filter it would go up to about 6,000rpm and loose power and sputter also it had some 4stroking through out and no matter how i tunned it it didnt want to pass 6,000......

The filter wventually was taken off and i replaced it with a huge brigs and straton one from a 5hp motor , this new filter was far larger and flowed way more air way easyer and suddenly the bike would rev as high as i could ever want it reaching 9,000rpms wile driving ¡!!! I even had to go up to a .74 main jet !!!! With the brigs filter it was too lean

Turns out that little filter that came on the carb as high flow as it looks could not flow enough air into the carb fast enough and was resticting the top end of the bike past 6,000 rpms

Davezilla · May 12, 2014

I agree there... a lot of those K&N clones are much more restrictive than they look partially due to their small size, but also the cotton gauze they put in them is too dense and won't let enough air pass thru, especially on a piston port engine that gets some blowback saturating the filter with the wrong type of oil for filteration. If you have limited space for a larger filter you can run an Outerwears pre filter over a gutted filter body and it'll flow really well with very little restriction and it filters the air quite well too.
I use an Outerwears rain sock on my Sportster's ram air filter and it flows plenty well and the filter inside never gets dirty. A lot of the Buell riders also just use a velocity stack and stretch an outerwears velocity stack bootie over the stack and don't even run a filter. they also make these pre filters in custom sizes or you can order them by the filter's dimensions. Here's a link for these... http://www.outerwears.com/proddetail.asp?prod=202452
And here's the link to order them by filter size if you want to burn the cotton out of a K&N clone and run this as a filter... http://www.outerwears.com/categories.asp?cat=12430 , They will even make you a custom one if you don't see your size and send them the dimensions you need.
I've used these for years to keep water from getting into my intake system if I get caught in the rain, but they flow so well I really don't need to take it back off.

SuperChris · May 12, 2014

Plug color only indicates proper heat range. Maybe you are to rich. I have the best luck on all my engines by reading the plug after cutting off the threads where they meet the ceramic. I'm new to this HT thing but on my outlaw kart engines I shoot for a heat range that keeps the ceramic almost all white and .5-1MM carbon band at the bottom of the ceramic.

mountain80 · Jun 7, 2014

It has been suggested to me by a motorcycle guru friend that possibly putting the bigger intake on and having a 150 psi cranking compression head is snuffing out the spark with the larger intake charge and to try dropping the gap to say 0.015'' or so and see what happens. Also the pipe primary length may be an issue, what are the rough lengths people are running on their sbp pipes from cylinder to beginning of the chamber???? I just measured mine and the centerline measurement from exhaust flange to beginning of expansion chamber is 14 inches.

Theon · Jun 8, 2014

Shorter header is likely to help give more top end.
I'm not running an SBP though.

Question for the gurus on intake manifold issues!

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