V-TWIN---MAYBE V-4

[Brian Rupnow]

Well, that wasn't too horribly painful. New tank of argon for the tig welder, $60, New tank of acetylene--$50, New hoses and fittings for oxy-acetylene rig $45, new acetylene regulator--$125, Hazardous material charge $10 and $35 tax. Grand total of $306.59. I'm back in business again, and I did get the silver solder to flow on that joint I was working on yesterday. Some of that material was 3/16" thick, so it took a lot of heat to get things to flow.

 

[Brian Rupnow]

And---TA-DA---We have a throttle return spring and bracket added.

 

[werowance]

i like it. the knurled tip that you are pulling to "give it more gas" is that an adjuster screw to for lack of better words adjust the idle speed? or is it just knurled to give you something to grab hold of to pull it?

 

[Brian Rupnow]

It is just knurled to look pretty and give me something to pull on. There are adjustments for fast or slow idle on the carburetors.

 

[Brian Rupnow]

Message here for Steve Hucks--Look at my spark-plug boots. Both sparkplugs are 1/4" thread. The boot on the left works fine. The boot on the right is shorting out right thru the boot material to the nearest cooling fin. It's like a miniature lightning storm when the engine is running. Do you sell spark-plug leads and boots like the one on the left?---Brian

 

[Brian Rupnow]

And now, it's time to go all scientific. The engine runs, but it doesn't run the way I like it to. The left hand cylinder runs like a champ, the right hand cylinder runs some of the time. Some of the time, it doesn't run. and when it doesn't run, it puts so much drag on the left hand cylinder that it stalls out under the load of carrying the non firing cylinder. Generally I use a degree wheel to set the valve timing, and lay the sparkplug out on the cylinder head so I can manually crank the engine over and watch to see when the spark occurs relative to the piston position. Somehow, that doesn't seem to be working for the right hand cylinder.---So, tomorrow I will once again get my degree wheel out and set the valve timing on the right hand cylinder. (The engine has a camshaft for each cylinder bank). Then I will pull the cylinder head off and put a dial indicator on the piston so I can set the spark timing up to occur exactly when the piston is at top dead center. The right cylinder has good compression, and the engine has "loosened up" considerably from running. I have tried a couple of different sparkplugs in that cylinder, and it makes no difference. Other folks have had better results with this style of engine, so I don't think that the problem has anything to do with the engine design.

 

[Vietti]

Switch carbs??

 

[johwen]

Why not just run the right cylinder on it's own. Leave the plug out on the left cylinder or just hold the exhaust valve open on the left. This would make it easier to ID the cause of the problem. Is the cam timing identical with the left side?

 

[metalmangler]

A bit of a long-shot, but would it be worth trying swapping the camshafts ?

 

[Brian Rupnow]

All good suggestions guys. I will let you know what happens.---Brian

 

[stevehuckss396]

Sorry Brian that one looks like an s/s boot from cncengines.com. the only thing I can offer is a longer plug. I have standard length, 1/8, 1/4, and 3/8 extended length.

Also I don't know if the auto parts stores in your part of the world has them but you can make a thicker boot using vacuum fittings.

 

[wgpeters]

Is there any chance that one of your cams is 180 degrees off? When the first cylinder fires. the next cylinder should be starting exhaust, not compression.

 

[rsholl]

Brian, couldn't find what spark plugs you are using. Let me know and I can send you another cap like you are using on the left cylinder.

 

[Brian Rupnow]

Roy--I don't know who made these plugs. I may have bought them from you. They have a 1/4"-32 thread and an electrode like an automobile sparkplug. The overall length including electrode is 0.987", and measured from the porcelain end the porcelain (including the brass button on top) is 0.463" long. The porcelain is 0.178" diameter. (It may not be porcelain, but it is white). I would like to buy a dozen of the boots, with a dozen 14" long wire leads attached. The leads measure 0.100" diameter. I have a different email since I last dealt with you, contact me with a price in American dollars at [email protected] ---Brian

 

[Brian Rupnow]

I'm back!!! I've had a good break away from this engine, found time to build a horizontal hit and miss engine, and haven't done much of anything since Christmas. It always scares me a little bit when I go two or three weeks without having to be in my shop!! This engine runs.--I've made two videos of what were wild, uncontrolable runs, but runs, nonetheless. Tomorrow I will take the sparkplug out of the right hand bank, and do my absolute best to get it running on the left hand cylinder. My engines always run sooner or later, and this one is going to be one of the "later" ones. First thing I will check is the ignition timing and the valve timing on the left hand cylinder. The way I have this engine set up, both cylinders are independent of the other, each cylinder having it's own discreet ignition system and camshaft and intake system. ---Brian

 

[Bentwings]

Sounds like a really neat engine post pictures when you can

 

[Steamchick]

Hi Brian. Just recapped message #346. Are you running a single carb? There is an odd comment that suggests you "swap carbs".. but I assumed this was one on the engine swapped with another on the bench.. But if I have missed something and you are on twin carbs, it may be the carbs not the ignition causing the different running on the 2 cylinders.
Anyhow . Considering your mis-fire or non-firing of one cylinder, on a V-twin with common carburettor the intake manifold be sensitive to fuel distribution, due to the timing difference between left to right and right to left intake opening separation intervals.
Even with twin carbs, my V-twin motorcycle is the devil to balance at idle, and just off idle. As it has a tachometer, it is necessary to pop the plug on one cylinder, set the idle on the other as a single, then do the opposite for the other carb. Then when both are connected and running, or mis-firing, I need to fiddle further to get some stability as with 2 cylinders running, the idle is too fast from setting as a pair of singles, and the off-beat of the Vee-twin means one cylinder always runs sweeter than t'other.
So, if you are running a single carb, when tuned right for the best cylinder, it won't run without misfires on the weaker cylinder - if like my bike - so instead you need to set the weaker cylinder at its best, and accept the better cylinder won't be perfectly tuned.
Anyhow, that's my experience of a vee-twin tuning.
K2

 

[Brian Rupnow]

I started out with a single carburetor and an intake manifold that fed both cylinders from the single carb. I have since moved up to two completely independent carburetors and no intake manifold except for short tubes that connect each carburetor directly to the cylinder it feeds..

 

[Steamchick]

Thanks Brian. I think that 1 carb per cylinder is a worthwhile improvement, given the quirks of the Vee-twin. On my Motorcycle engine, I still re-tune the carbs for idle every year, then tweak them for Spring, Summer and Autumnal use as the town idle temperatures change! For anything where I am at more than 1/4 throttle, the carburation is "sufficiently within limits" that I never change it, but after Spring riding, with stable tick-over, the bike goes off noticeably when the temperature gets over about 17deg.C, so gets re-set for Summer, then come September it needs tuning again, when the air cools, as otherwise it simply won't idle securely. And that's how it has been for the last 25 years of ownership! Also, I knew the same model of bike in the late 1980s that a work colleague owned. I spent a whole year, re-setting the idle for him almost weekly, as the weather changed! So it wasn't just my bike. And it was an 1/8th of a screw on one or other carb just to stop it from stalling, apparently at random. Then it would be fine for a week or 2 until a dramatic weather change...
Everyone else seems to manage by just setting a fast idle - that causes popping and banging on over-run. I even here it today with carburetted Harley Davisons... Their riders appear to have no mechanical sympathy for bad tuning? Of course, super electronic controlled fuel injection has countermeasures for all that...!

Have fun!
K2

 

[animal12]

As long as they can ride their bike to the dealership to hang out with other " biker's " on the weekend A sputter or two is fine . I have a 46 that I'm getting to tear down all the way & replace worn out parts & such . Fortunatly with a bike that age I never have to go to the dealership .
animal