A little be late in responding but heres what I found, no problem with 90 degree elbow, other issues from airfilter not being matched for the carb I used that has no mixture adjust needle valve screw.
No problem, I did use a Tecumseh 90 degree elbow that came off a Toro Mower and used it on My Briggs 3hp 4stroke.
It took making a small adapter plate to use as it was for screw hole 90 degrees turned for the two screws (not the 90 degree bend). I used flat head screws and countersunk them so the flange would not have bolts heads making the adapter unusable to attach to the intake on the engine. The thread and nuts with lock washers are on the oppisite side of the adapter away from the engine not seen. They don't hit or interfere with anything, just hold the adapter onto the 90 degree elbow as one unit.
Then it got a little more complicated, not though because of using the 90 degree elbow or the simple adapter plate, but that my engine was on about a 17 degree tilt aft.
That got me thinking what’s wrong with another adapter plate to cancel that tilt out so the float in the bowl on the carb is happy. I made that adapter.
Then the airfilter, I had none that fit the carb as before I was using an older vacujet carb that used an integral gas tank and an oil bath airfilter and used a choke not primer bulb. That setup was going to not fit in the frame due to the seat post down tube with or without the 90 degree elbow so I have a float bowl carb with separate gravity feed gas tank on top tube.
I made use of the airfilter housing from the Toro Mower that was modified to fit. Problems arose when I thought I needed an airfilter that had an integral primer bulb that worked by connection to the carb. I made a third adapter that got that solved.
Then the real deal was when I had it running but had bogging down at high rpm even without any load. I tried the timing at the breaker points and almost had it licked, but wanted it perfect.
I tested without any airfilter on non-windy day and no dust around with engine stationary. Ruining an engine is just that simple with dust getting in, so don't try this without thinking it out first! It worked fine. I thought maybe the foam airfilter was not giving enough air and was too rich a mixture. I was not going to try to change jets as the lawn mower shops are not really set up to help there, except to sell a new engine or have you use all one brand on an engine.
Since the cheap carb has no adjustment needle valve (which in hind sight I would have spent additional 20 bucks on) I thought then get a pleated paper airfilter as it probably is less restrictive and would solve the richness issue.
Ebay found the two part housing with primer bulb for the Briggs at 1/5 the cost of new, local hardware store the new pleated paper filter, and very thin foam prefilter new from lawn mower shop and it roars just as it did with the prior vacujet carb with integral gas tank and oil bath airfilter.
So many things can be changed and there are some that cannot. The 90 degree elbow surely had no change as I could tell. They do say the length of the intake as it gets longer give more low rpm power and shorter give high rpm power. Small length changes I don’t think are even noticeable.
Measure Twice's Thread: Motor Bike DIY'er build to add side car maybe?
Probably not going to build side car as it was just a though if the dirt bike design adapted for art vehicle got too heavy and I could not ride it. I even thought of training wheels that had shock absorbers but I'll see. I want to change the thread name and emailed internally to the site help and never got an answer so it stays the same name.
The working bike before I adapt it to be geared down using more pulleys and jack shafts to 47:1 ratio for parade speed is shown on Page 3, Post #28, Picture 3 of 5.
http://motorbicycling.com/showthread.php?t=29678&page=3
Like to hear how the adapter works!
MT
