Topic: Kickstarting big bore/ Hi-Po motors

[oldfett]

I've been curious about this for awhile. Do all of you with 836 (or more) motors, those with high compression motors or overall High Performance ever kick-start your bikes? If so is it an absolute nightmare or just a little bit harder than a stock 750? I would assume that it would be a beast of a task but I don't know.

[HondaMan]

It's not bad. The electric starters still work on the 836 engines, up to about 10.25:1 compression ratio: above that, it can wear on the starter clutch after a while.

I'd recommend cryo treatment or center-drilling of the kickstarter shaft to increase it's strength, since you'll have the engine apart anyway...it's the same shaft that spins the gear that drives the oil pump, a pretty important part, there. 

[oldfett]

It's not bad. The electric starters still work on the 836 engines, up to about 10.25:1 compression ratio: above that, it can wear on the starter clutch after a while.

I'd recommend cryo treatment or center-drilling of the kickstarter shaft to increase it's strength, since you'll have the engine apart anyway...it's the same shaft that spins the gear that drives the oil pump, a pretty important part, there. 

How do you center drill the kickstart shaft and how does this strengthen it?

[HondaMan]

A hole down the center of any shaft increases the surface area of the shaft: this is where most of the strength lies.

In industry, you'll often find center-drilled bolts in high-stress motor mounts, for example, where previously the stresses broke the original bolts. It's an old WWII trick. 

[oldfett]

A hole down the center of any shaft increases the surface area of the shaft: this is where most of the strength lies.

In industry, you'll often find center-drilled bolts in high-stress motor mounts, for example, where previously the stresses broke the original bolts. It's an old WWII trick. 

So any decent machine shop could accomplish this? So for top results I could do this and then send it out for cryo treatment, correct?

[Kframe]

A hole down the center of any shaft increases the surface area of the shaft: this is where most of the strength lies.

In industry, you'll often find center-drilled bolts in high-stress motor mounts, for example, where previously the stresses broke the original bolts. It's an old WWII trick. 

So any decent machine shop could accomplish this? So for top results I could do this and then send it out for cryo treatment, correct?

Anyone with a bit of skill, a drill press, and a homemade jig could bore bolts.  But, yeah, any shop could do it too.

Now, as far as cryo, unless you've got a jug of LN2 that we don't know about, you'll have to send that out.
 
-K

[oldfett]

Now, as far as cryo, unless you've got a jug of LN2 that we don't know about, you'll have to send that out.
 
-K

Unfortunately I do not have that jug lying around. I'll have to find a place to send it but I would like to send a few more parts out.

[754]

I ran kick only on an 836 for many years. Kick only on most of the 750s I had..

[Gamma]

So what do I do with the LN2.  What's the process?

[MCRider]

So what do I do with the LN2.  What's the process?

I have 2 kickstart shafts that have been shotpeened and cryo treated for strength. No center drilling, but that can still be done. Though I think it would be overkill.

I have 3, but ones for me and I had 2 more done to meet the minimum shop charges.

As has been said, the electric wioll work with an 836. I have an 888 and always used the electric. Also, you can use the electric and supplement with the kick like Bronson did on his Sportster back in the Then Came Bronson TV show.

I thought I had these priced on the forum, but i have searched everywhere and can't find a mention other than i was going to do it. So I'd say $60 + $10 S&H. If you can find on the forum where i had a lower price, I will honor that.

[72 yellow]

I've been curious about this for awhile. Do all of you with 836 (or more) motors, those with high compression motors or overall High Performance ever kick-start your bikes? If so is it an absolute nightmare or just a little bit harder than a stock 750? I would assume that it would be a beast of a task but I don't know.

A friend had a 64 Sportster that I used to ride.  It had 12-1 compression, sifton cams, and a magneto.  The starting drill had to be followed perfectly.  Fuel on, key on, prime, use left grip to retard the mag (the most important to avoid a vicious kickback), slowly move kickstarter down to find compression, then a full kick.  No callouses on your right thumb from electric start.  Ah, the old days.  That's why my other bike is a 650 BSA.  Keeps the right leg in shape.   

[HondaMan]

I've been curious about this for awhile. Do all of you with 836 (or more) motors, those with high compression motors or overall High Performance ever kick-start your bikes? If so is it an absolute nightmare or just a little bit harder than a stock 750? I would assume that it would be a beast of a task but I don't know.

A friend had a 64 Sportster that I used to ride.  It had 12-1 compression, sifton cams, and a magneto.  The starting drill had to be followed perfectly.  Fuel on, key on, prime, use left grip to retard the mag (the most important to avoid a vicious kickback), slowly move kickstarter down to find compression, then a full kick.  No callouses on your right thumb from electric start.  Ah, the old days.  That's why my other bike is a 650 BSA.  Keeps the right leg in shape.   

The first '66 (or maybe it was a '65) Sporty I had in the shop when we started handling them in 1972 had 10:1 pistons, too. I didn't know about the retarder (yet), and dropped on the kickstarter (after the prime) with all my 125 lbs, knowing about the 10:1. It stopped me halfway down, buckled my knee, then casually flipped me off the back of the bike by my thigh. It took two weeks to get over that bruise! 

Talk about embarrassed...at least I was alone at the time!

[paulages]

the cb500/550 is much kinder with the kickstart. mine has 10.6/1 CR, and i could practically kick it over with my arm.... if it would start that easily cold. anyway, the BSA is another story. takes all of my weight and must be at the top of a compression stroke or else it might try and kick back the other way.

[Terry in Australia]

My 836 with 12.5:1 RC/Arias pistons has noticeably more compression than my F2 or K0, but the starter motor is still working fine after a couple of years of use. I don't ride it every day though (or even every month for that matter) so with more use it might fail, I guess. I've never heard of a CB750 kicker shaft failing though, that's a new one to me? Cheers, Terry.

[mec]

A hole down the center of any shaft increases the surface area of the shaft: this is where most of the strength lies.

In industry, you'll often find center-drilled bolts in high-stress motor mounts, for example, where previously the stresses broke the original bolts. It's an old WWII trick. 

sorry, can´t agree at all.
drilling a shaft you will save weight and the weight strength ratio will be better, but the absolutely strength will go down. removing material will overrule increasing surface.

drilling a screw will make it more elastic what MAY prevent cracking, because this puts more load on the screws in the neigbourhood. but there is a constructively issue from the beginning.


mec

[Terry in Australia]

Not to mention engine oil running out of your kicker shaft.........

[MRieck]

The cam has a direct effect on the effort required

[MCRider]

My 836 with 12.5:1 RC/Arias pistons has noticeably more compression than my F2 or K0, but the starter motor is still working fine after a couple of years of use. I don't ride it every day though (or even every month for that matter) so with more use it might fail, I guess. I've never heard of a CB750 kicker shaft failing though, that's a new one to me? Cheers, Terry.

I've seen two personally. There was a rash of broken ones on the forum about 1 year ago. A poster had bot a used engine with a flaccid KS. Twas a broken shaft. The motor will still run fine, the KS just hangs limp at the side.

RC used to sell heat treated, shotpeened ones.  I looked into replacing that, but the heat treating was too hard to get done on a small production run, so I opted for the Cryogenics/shotpeen approach.

I agree though that the electric is pretty strong. On my 888cc/10.5:1 CR, the starter motor never failed in 50K. The spring/roller/cap combo had to be replaced once, but that can happen on a stocker.

I did often kick and electric together but that was as much for the visual effect as to actually get it started.

[72 yellow]

I've been curious about this for awhile. Do all of you with 836 (or more) motors, those with high compression motors or overall High Performance ever kick-start your bikes? If so is it an absolute nightmare or just a little bit harder than a stock 750? I would assume that it would be a beast of a task but I don't know.

A friend had a 64 Sportster that I used to ride.  It had 12-1 compression, sifton cams, and a magneto.  The starting drill had to be followed perfectly.  Fuel on, key on, prime, use left grip to retard the mag (the most important to avoid a vicious kickback), slowly move kickstarter down to find compression, then a full kick.  No callouses on your right thumb from electric start.  Ah, the old days.  That's why my other bike is a 650 BSA.  Keeps the right leg in shape.   

The first '66 (or maybe it was a '65) Sporty I had in the shop when we started handling them in 1972 had 10:1 pistons, too. I didn't know about the retarder (yet), and dropped on the kickstarter (after the prime) with all my 125 lbs, knowing about the 10:1. It stopped me halfway down, buckled my knee, then casually flipped me off the back of the bike by my thigh. It took two weeks to get over that bruise! 

Talk about embarrassed...at least I was alone at the time!

I even learned to use my left leg to kickstart this beast from a couple of oldtimers in a outlaw club.  Kind of awkward, but can be done.

[MCRider]

I've been curious about this for awhile. Do all of you with 836 (or more) motors, those with high compression motors or overall High Performance ever kick-start your bikes? If so is it an absolute nightmare or just a little bit harder than a stock 750? I would assume that it would be a beast of a task but I don't know.

A friend had a 64 Sportster that I used to ride.  It had 12-1 compression, sifton cams, and a magneto.  The starting drill had to be followed perfectly.  Fuel on, key on, prime, use left grip to retard the mag (the most important to avoid a vicious kickback), slowly move kickstarter down to find compression, then a full kick.  No callouses on your right thumb from electric start.  Ah, the old days.  That's why my other bike is a 650 BSA.  Keeps the right leg in shape.   

The first '66 (or maybe it was a '65) Sporty I had in the shop when we started handling them in 1972 had 10:1 pistons, too. I didn't know about the retarder (yet), and dropped on the kickstarter (after the prime) with all my 125 lbs, knowing about the 10:1. It stopped me halfway down, buckled my knee, then casually flipped me off the back of the bike by my thigh. It took two weeks to get over that bruise! 

Talk about embarrassed...at least I was alone at the time!

I even learned to use my left leg to kickstart this beast from a couple of oldtimers in a outlaw club.  Kind of awkward, but can be done.

The left leg kick is popular with the dirt bike crowd as far back as the 1970s, when I learned of it. Dirt bikes were often too tall to straddle and rt leg kick. The side stand was either non existent or too weak to trust.  So you stand off to the rt side and kick it with the left. I would do that on the 750 for effect as well.

[Terry in Australia]

I always use the kicker first with the ignition off to get the oil circulating, normally a dozen or so kicks first with the fuel on and the choke on too (not necessary on my 836 with the Keihin CR29's, they run way too rich anyway) and then I'm happy to use the "electric leg" to fire it up.

I'm always surprised that people don't do this if they have the opportunity, particularly on bikes that aren't used on a regular basis, "dry starts" can do so much damage to engines, I think all bikes should have a kicker fitted, just to get the lube circulating. Cheers, Terry.

[754]

Long duration cams on some engines REDUCE cranking pressure, so it is probably so on these engines too... that coupled with higher compression, may make it only slightly harder than stock.. except when first built they tend to be tighter.

 On a 1-10 with 1 being easiest ..a 750 is a 2 or 3..

[wannabridin]

The cam has a direct effect on the effort required

mike,

could you elaborate on this more?  i'm considering taking off the e-start to save crank weight and dead weight...

[MCRider]

The cam has a direct effect on the effort required

mike,

could you elaborate on this more?  i'm considering taking off the e-start to save crank weight and dead weight...

I mentioned this in earlier posts as well. With more overlap and lift (hot cam) at low RPMs (kicking speeds) you lose a lot of pressure out thru the valves and that makes the kicking effort actually easier than on a stocker. But it all depends on the total set up.

[Terry in Australia]

That wasn't the case with my 836 with the RC/Arias pistons, Mike's first "Stage 3" head and Megacycle 125/75 cam, it takes most of my 280 pounds to kick that sucker over!