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Reducing BSA 441 Compression
#821891 08/31/20 3:19 pm
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Hi - This is my first post. I have a 1967 round cylinder BSA 441 Victor Special. There is so much compression that the motor is *VERY* hard to start. It has an electronic ignition. Timing is good.

It has been suggested that I put a cylinder spacer under the cylinder. I found a company that manufacturers these spacers in any thickness that I want.

Does anyone have experience with this? If so, what thickness would you recommend?

Also, another issue... The kick starter is only 6" long. My brother's BSA & Triumph are 9" which obviously gives you more leverage. I plan to replace my 6" with a 9" kick starter. Any comments?

Thanks,
Dean

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Re: Reducing BSA 441 Compression
DeanInAnnapolis #821894 08/31/20 3:32 pm
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i always said i could leave the key in my '68 victor because i knew a thief would never get it started.
don't you have a compression release on the handlebar?

Re: Reducing BSA 441 Compression
DeanInAnnapolis #821900 08/31/20 3:52 pm
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A B50 is a little different from a B44 in terms of starting. The "gearing" between the kickstarter and the motor on the B50 doesn't spin the crank very far on each kick, so it has to be just right (compression release, spark, fuel) to start ... most people modify the carb a bit to get it to start hot.

The B44 should be a pretty easy starting bike. Every one I've ever ridden was an easy starter.

You push down the kickstart lever so that it stops just before the compression stroke, pull in the compression release lever so that the kickstart lever moves again, EASE the engine over compression, release the compression release, let the kickstarter back to the top, and give it a good kick. I've never had to do it more than once or twice; if you do, there's something wrong.

I wouldn't modify the engine (reducing the power) unless you're pretty sure that the correct starting procedure isn't working. I'd chase that all the way down first ... !

Lannis


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Re: Reducing BSA 441 Compression
Lannis #821903 08/31/20 4:12 pm
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If you don’t have a compression release you can put the bike in gear ( I use second) and roll it backwards. Easy enough to do sitting on the seat. When you roll backwards ( don’t pull in the clutch) the engine compression will stop you. At this point the piston is located just past TDC like it would with a correctly used compression release.

That said, I added a “ spacer” ( thank you Craig Holder) where my barrel gasket would have been and lowered my compression to 8:1 on my BSA B25 trials bike. I did have to lengthen the push rods when I did it.

I agree with a Lannis, I wouldn’t be modifying the engine until I knew I was using the correct unit single starting procedure.

Take and post a photo of the kicker you want to swap out. Could be me or somebody else on here has what you’re looking for. I’ve had to go to a shorter kicker on my B44 sidecar rig because of clearance issues. Keep in mind the earlier kicker quad’s shaft is a smaller dia than the later models. 5/8 vs 3/4.......or something like that. It’s easy enough to swap side cover and quad so you want to know what you have in place now.

Probably more than you wanted to know.....but

Gordon

Last edited by Gordon Gray; 08/31/20 4:17 pm.
Re: Reducing BSA 441 Compression
DeanInAnnapolis #821911 08/31/20 5:02 pm
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Dean, I have NOS longer kickstarts that are made for the 5/8" kickstart shaft. These are 7-3/4" long and are difficult to find (when you need one).
I identify them as 41-3020-ASSY and sell them for $ 90.00. There aren't really any other options unless you buy a new 3/4" kickstart quadrant and then also replace the outer timing cover with a later one that has the 3/4" bushing for the larger shaft. All doable but a bit more expensive than getting the kickstarts I have in stock. You can peruse my website to see all the items I have for the unit singles: www.bsaunitsingles.com

As folks say above there are other reasons for your bikes hard starting other than the kickstart lever length, although longer levers do help.

Listen to Gordon about finding the perfect piston location for starting. It is easier to get the piston in to optimal position doing that than using the valve lifter. Also the slide has to be set just right so you can start without giving the bike any throttle.Treat the throttle like it is rigid when starting. No twisting when kicking!!

Peter


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Re: Reducing BSA 441 Compression
DeanInAnnapolis #821912 08/31/20 5:09 pm
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As Peter says the throttle position is critical, to take the guesswork out I fit an extended throttle stop screw and turn it in 1 to 2 turns for starting and no need for hand on the throttle, you can use a gloved hand on it to return the idle to its normal speed.

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Re: Reducing BSA 441 Compression
kommando #821919 08/31/20 6:17 pm
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Originally Posted by kommando
As Peter says the throttle position is critical, to take the guesswork out I fit an extended throttle stop screw and turn it in 1 to 2 turns for starting and no need for hand on the throttle, you can use a gloved hand on it to return the idle to its normal speed.

Probably one of the hardest things for me to remember. I’ve owned and ridden BSA unit singles since 1969. NOT touching the throttle is STILL a pain for me to remember.

Now.....picture a group of your friends.....all twins guys. Late at night, been lots of beer consumed. Your B50 floods because you have the float level to high ( thank you Mr Healy). You KNOW how to clear it out. But you listen to your TWIN friends that keep insisting that you have to open the throttle WFO for it to start. Well.....it ain’t gona do that.....it’s a unit single. The joys of a BRIT BIKE hobby..ya gota love it.

Good luck.... you’ll get it. None of us are born knowing this stuff. We’ve all been down that learning curve.

Gordon

Re: Reducing BSA 441 Compression
DeanInAnnapolis #821923 08/31/20 7:12 pm
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I've successfully been able to start B50s cold by following the rules here, and I flatter myself that with a well-sorted B50 like Mr. Mike's or Ben Strain's (the last two I rode), I can start it hot by cracking the throttle with the idle stop and then twiddling it back once it's running (which is what the big Yamaha singles do with a "hot start lever" that cracks the throttle for hot starting).

But how do you start a flooded B50 (hot or cold) if you don't open the throttle like a twin?

Lannis


"Why do you wear that thing, Dobby?" "This, sir? 'Tis a mark of the house-elf’s enslavement, sir."
Re: Reducing BSA 441 Compression
DeanInAnnapolis #821924 08/31/20 7:50 pm
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If my B44 floods I use the decompression lever and kick with throttle fully open ignition on, no resistance so kicking is easy, when there is loud bang out the exhaust it tells me the flooding is cleared. I then follow the normal starting routine. Good effect in pub car parks to see all the heads looking for where the loud bang came from.

Re: Reducing BSA 441 Compression
DeanInAnnapolis #821926 08/31/20 8:42 pm
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We used to call those short kick-start levers "leg breakers."

I think they were hold-overs from C-15s and B-40s.

Re: Reducing BSA 441 Compression
Lannis #821931 08/31/20 9:12 pm
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Originally Posted by Lannis
I've successfully been able to start B50s cold by following the rules here, and I flatter myself that with a well-sorted B50 like Mr. Mike's or Ben Strain's (the last two I rode), I can start it hot by cracking the throttle with the idle stop and then twiddling it back once it's running (which is what the big Yamaha singles do with a "hot start lever" that cracks the throttle for hot starting).

But how do you start a flooded B50 (hot or cold) if you don't open the throttle like a twin?

Lannis


Fair question Lannis.........YOU DO open the throttle WFO........BUT it ain't gona start like that.

You leave the key on.......pull in the decompression lever and leave it pulled in ( ya see the bike isn't gona start like that) you cycle the kick start lever.....you are NOT trying to start it your just trying to clear the cylinder. 9 times out of 10 when the cylinder clears out ( not flooded any more) ......there will be a "slight" cough as the mixture finally fires ( remember the key is on). This can take 10 kicks/cycles but remember you're not trying to start it....just getting fresh air into the cylinder. You have the decompression lever pulled in....there is little resistance...it's easy. Once you get to that point ( pop or bang) it's ready to start using your normal singles starting procedure minus the tickle. There has been times I got a loud pop like kommando says...other's it's just been a small pop/puff, I've also had it do nothing.....but after 10 kicks/cycles it should be clear.

You can ask me how I know.......but you already know that.

Gordon....PROUD to be one of the BSA unit single guys

OOPS.........maybe I should read ALL the replies BEFORE I type.......kommando is spot on. AND if it wasn't for one of those short kickers....my sidecar rig wouldn't had worked the way it does. I have never had a problem with starting that bike with that kicker.

Last edited by Gordon Gray; 09/01/20 10:35 am.
Re: Reducing BSA 441 Compression
DeanInAnnapolis #821946 09/01/20 12:03 am
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Going back to the original post ...... when I first got my B44 there was no decompression lever fitted " Never needed one" said the seller. Not surprising as it had two broken rings, an egg shaped barrel, and valves that were only valves by name not by function.
By the time I had it all sorted there was, and still is, no way in hell to kick it over compression without the deco lever. Fitted one and still had "issues" starting the damn thing even after fitting electronic ignition (Vape). Then I saw this:- https://www.youtube.com/watch?v=BG57INfbpCA .

It seems how far past TDC you take it before "the big kick" actually matters. My bike starts first kick when warm and max two kicks when cold, though you do have to kick it like you mean it! Carb set up is critical and like Kommando I have an extended throttle screw but only turn it 1/2 turn at most then NO throttle on the twist grip AT ALL, or it simply will not start.

Re: Reducing BSA 441 Compression
DeanInAnnapolis #821952 09/01/20 12:41 am
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I never use the decompression lever wether it be B40/44/50 or B31/33, I always turn the crank till it’s on compression then leave the weight of my foot on the lever, it slowly but by bit turns the crank over then when it starts to do it a bit faster, bring it back up to compression and kick. I always find if I use the decompression lever then I always stop the crank in the wrong place. So for me I’ve found it less likely to start.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Re: Reducing BSA 441 Compression
DeanInAnnapolis #822038 09/01/20 8:49 pm
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I have a B44 and a B50. I also have had a bad left leg since I turned 17, so I kick start bikes by standing off to the side. That makes the rolling backwards method a little bit more tedious, so I simply use the compression release the way it is intended if there is one. I am also a big guy (275 lbs) and I have rarely had trouble pushing a bike through compression without using the compression release, UNTIL I got my B50 going with new rings, valves and guides. It is the only bike that I have ever seen where I can stand on the kicker on the compression stroke and it doesn't budge. If while kicking it, you don't have it in the right spot, and it comes up on compression, it feels like the engine locked up. Use the compression release and it starts and seems fine. I have never seen that type of compression before.

Ed

Re: Reducing BSA 441 Compression
DeanInAnnapolis #822050 09/01/20 10:46 pm
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Yes there is a compression release on the handle bar but from the starting instructions from the original manual which I have, it says to disengage the release after positioning the piston after TDC. That is where part if the problem seems to stem from.

Re: Reducing BSA 441 Compression
DeanInAnnapolis #822054 09/01/20 11:09 pm
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Originally Posted by DeanInAnnapolis
Yes there is a compression release on the handle bar but from the starting instructions from the original manual which I have, it says to disengage the release after positioning the piston after TDC. That is where part if the problem seems to stem from.


DeaninAnnapolis.......that sounds right.....as long as we're talking about the same "disengage"?

You push the kickstart until you feel it come up on compression, the way you're describing it that should be easy enough to find.....the kicker comes to a stop and a LOT more pressure would be needed to move it further. If you can ( and your not at the bottom of the kicker's stroke) you hold your foot and the kicker right there and then pull IN the compression release lever. With your foot still on the kicker.....now there is no compression you continue pushing the kicker and you'll feel the piston move past TDC. Meaning you were at top dead center when the kicker first stopped....now you just need to move it a little past that. Now you release the compression release, take your foot off the kicker and let it return to it's normal position......then kick it through to start it. All your trying to do is find that sweet spot just past TDC so you're not trying to kick against the compression to start off with.

IF......you will sit on the bike. Put the bike in second gear with the clutch engaged. Use both your feet and push the bike backwards....you will hear/feel the engine turn over. When the bike stops....and it will if you have as much compression as you say.....THAT is the point where you want the piston. Put it back in neutral, key on, tickle and kick. IF you still feel to much compression......you might need to do something different.

Just trying to help........Gordon

Last edited by Gordon Gray; 09/01/20 11:10 pm.
Re: Reducing BSA 441 Compression
Gordon Gray #822098 09/02/20 3:35 pm
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Thanks Gordon. Pushing it backwards until it stops sounds like a great idea. I'll try it. I think I'm still going to get a cylinder spacer and install it. I can get one that is 1.22mm or one that is 1.55mm. I think I'm going to start with the big one and see if that helps also.

Re: Reducing BSA 441 Compression
DeanInAnnapolis #822100 09/02/20 3:48 pm
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You’re welcome Dean, just trying to help. It would be easier if we were standing around the bike. But you’ll get this.

If you add a spacer you “might” have to lengthen the push rods. I just popped the cap off and added a piece of the same material used for the shim, then glued the push rods cap back on.

I did that on a BSA B25 trials bike I had to “tame it down” a bit. Worked fine for what I was trying to do.

Good luck and let us know how it works out.

Gordon in NC

Last edited by Gordon Gray; 09/02/20 3:49 pm.
Re: Reducing BSA 441 Compression
kommando #822112 09/02/20 4:50 pm
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Originally Posted by kommando
If my B44 floods I use the decompression lever and kick with throttle fully open ignition on, no resistance so kicking is easy, when there is loud bang out the exhaust it tells me the flooding is cleared. I then follow the normal starting routine. Good effect in pub car parks to see all the heads looking for where the loud bang came from.

I like this! Is it a feature offered by all B44s? A proper motorcycle needs a proper starting technique, none of this pressing of buttons nonsense. I looked at buying a B44 or a B50 several years ago, but the bikes in my price range were not the most handsome of machines. I probably need to see beyond the ugliness.

Some owners of AMC 500 singles decompress, pump the kickstart quickly to spin the flywheel up, then release the decompressor.

CCM apparently deleted the kickstart on their later motocross bikes (modified BSA engines) on the basis that no rider would be able to restart the bike out on the course. Also deleted 4th gear as I recall, 3 gears being sufficient. Rolling thunder compared to the two strokes from other countries, particularly on a course that included trees.

Re: Reducing BSA 441 Compression
Dibnah #822116 09/02/20 4:57 pm
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Originally Posted by Dibnah
Originally Posted by kommando
If my B44 floods I use the decompression lever and kick with throttle fully open ignition on, no resistance so kicking is easy, when there is loud bang out the exhaust it tells me the flooding is cleared. I then follow the normal starting routine. Good effect in pub car parks to see all the heads looking for where the loud bang came from.

I like this! Is it a feature offered by all B44s?

All Unit Singles with a decompression lever and I guess any other single with an exhaust valve lifter. Keeping the ignition on gives the bang as soon as the fuel is away from the spark plug, that then ignites all the unburnt fuel blown out into the exhaust pipe for added effect.

Re: Reducing BSA 441 Compression
DeanInAnnapolis #822122 09/02/20 5:46 pm
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The manual advance / retard on my AMC 500 single enables me to summon backfires as required when travelling, although I am wary regarding the possibility of a backfire that might blow the silencer into the path of other traffic.

The single backfire blast from a Brit single is useful for keeping tailgaters at a distance; the pops and coughs generated by some modern modified cars are laughable in comparison.

Re: Reducing BSA 441 Compression
Peter Quick #822458 09/05/20 8:17 pm
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Hi Peter - I am going to buy the 7 3/4" kick starter with a 5/8" shaft unless you have a longer one. I also want to inquire about a stock piston and ring set for the 1967 BSA 441 Victor. Do you have a part # for that as well?

Thanks,
Dean

Re: Reducing BSA 441 Compression
DeanInAnnapolis #822638 09/07/20 12:36 am
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Hi Dean,

PM sent. Check your messages

Thanks,

Peter


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2500 BSA part numbers with inventory in stock just for the unit singles!

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