Building a Ht Motorized Bicycle or Three.

[Davezilla]

Looks good but maybe that pipe is too restrictive right at the connection where it's welded to the stinger? it looks like the exaust has to hit the inside of that dual header at a perfect 90 degree angle and the turbulence caused by that may be restricting the flow at higher rpms enough to lose some top end. If you could fab up a Y pipe and weld it in to get rid of that spot where the exhaust hits the side of the dual header it could bring your top end back to what it was.
But try leaning it out a little on top first to see if that cures it... Sometimes even a small change in the airflow is enough to throw off the mixture too.
That pipe might look good and sound a lot quieter as well as flow as good as before also if you cap off the end and put a side bleed stinger on it's belly section. I've seen some side bleeds that are almost quiet enough to not even need a muffler.

 

[Theon]

Was considering a side bleed, I'm not sure I can be worried about loosing a little top end, as it was built for mid range.
I have used this muffler before at 9500 but have since stuffed a whole SS scourer in each chamber. The more restrictive stinger/muffler may have smoothed my power delivery a little, but I still got her to 9000, however power started to drop off at 8500. Which is what I was expecting from this motor.

 

[Davezilla]

If that puts you where you originally planned and the mid range is where you want it or maybe better then it might be best to leave it as is. It really won't hurt anything if you plan on running it at lower rpm's and just use the top end for short bursts.

 

[Theon]

It's more than fast enough off road.
And geared wrong for the street.
I don't want to change anything other than experiment with the timing now and see if I can improve the low down that way, again not to worried about loosing top end, however hoping a properly tuned adjustable CDI may improve both.
And possibly a lower gear for the peddles to help overcome the compression and make it easier to prevent a stall with trail riding.

 

[Davezilla]

Sounds good to me...
BTW.. I got my Rocket CDI working the other day so I'll be able to give it a fair report after I seal it up and install it again. turned out to be a bad mag coil on the new engine, then I swapped it out with a known good one and it still didn't fire from that cdi so I put the stock CDI back on and it runs.
Anyway, it was raining and couldn't ride, I got bored and decided to play with the CDI some more and found the red and black wires were reversed so I rewired it on my other engine and turned it over with a cordless drill and it was firing just fine.

 

[sub66]

i have cruise issues now. my bike rolls so fast.... im frustrated.
i did trench boost ports first. terrible bottom end. now the cruise issue either is the diaphram carb or good boost ports running it lean on cruise. or both and no load.

motor runs great at 2200 just cant cruise on low throttle or anywhere. crack crack instead of pop pop trying to cruise. roll on the throttle a hair and problem stops....runs great.

am i being to critical ? im frustrated like i need to start all over or gear faster to 25t just so i can stay on throttle.
frustrated

 

[Theon]

Lean Mid?
Not familiar with your carb sorry, is this the walbro?

 

[sub66]

yea the walbro. the midrange is great and everywhere else. i just cant cruise but offroad low end is fantastic really. i saw a pipe that is getting me excited. and some headstuds too. i have the 2 stroke cruise blues a bit anyway today. but so many pipes...

 

[Theon]

I'm having carb blues today also.
sometimes bike will start, sometimes not.
Runs great when it will start?
Been swapping carb bits?
Changed the rotor today for one with less advance, think it improved low low down and idle
Havn't got much riding this arvo, mostly peddling and tinkering. .

 

[sub66]

anytime i had that issue it was the pulse line leak or elsewhere on engine.

but i did a carb cruise mod on a tilly before. maybe i will do that again.

i have 2 issues w the pipe i like. it doesnt fit my bike? and its 100 bucks by the time it gets here. oouch. its 2.5 feet long...... anyway.

ur block is 360 degree induction right? if the pipe is correct it should run great but im worried about the boosters should be tranfers not boosters. cant hurt to try.

i looked at rse and alot of extreme prices w bs all over it.

l8r t

 

[Theon]

I think your right about the BS.
I was wondering if I just wasn't getting good enough spark at low (starting) revs to overcome compression, have blue spark but only small.

 

[sub66]

hmmm well i liked the stock plug w factory gaps. it is supposed to be that way contrary to popular belief. if u asked me.

i have had my bike cruising at and accel below 1500 rpm lately. the tach cant keep up. but i see no problem with stock ignition map. only bad tuned intake and exhaust. advancing timing raises issues. reversely dutuning/retard timing hides flawed tunes. thats all they do. just a band aid. better to move stock rotor period as adjusting band aids is for women/ like make-up for homely girls

 

[sub66]

i got a 100 dollar pipe . yikes. and headstuds. been a great day. thats it for me. i was drooling over this pipe for weeks.

 

[Theon]

I believe 20 deg advance is the sweet spot.
More than that ain't going to make it run better.

 

[sub66]

i argue that i am correct fundamentaly. did u see that rse exhaust theon? what do u think of it please???

 

[Theon]

It's long.
Don't know if I could have the pipe hanging out the back that far, might be OK on some bikes.
I hope his $127 'balanced' cranks don't vibrate at 6000 like mine does!

 

[sub66]

yea it is loong i just saw the rse yesterday and it was like wow thats funny.

 

[sub66]

pardon me but what do u think the powerband would be? 8000 rpm long? im trying to guess

 

[Theon]

It's in the carb?
If I choke the carb she burst to life, then dies again if I take my hand away.
Not pulling fuel through without extra vac.

 

[Theon]

Have no idea of powerband on RSE pipe,