ironhead with a servi-car rear end

[don56]

I mated a servi-car rear end to my 74 sportster, it has a weird issue with 2nd gear. Has anyone that has combined these two have any problems?

All gears work fine but when I'm in 2nd, the motor rpm's won't stay constant, it's as if I'm twisting the throttle back and forth, the bike jerks. Makes no difference what speed or rpm I'm at when I shift to 2nd the bike starts this jerking motion, the engine rpm's go up and down, I shift to 3rd and all is fine. It's not popping in and out of gear, it's like give it gas, stop, give it gas, stop, all the time while in 2nd.

I have tried different drive gears, it now has a 19 tooth sprocket, stock rear sprocket.

Any ideas?

[Jack Klarich]

What happens if you keep pressure on the shifter?

You could have a bad shifter dog on second gear from years of abuse?

[don56]

What happens if you keep pressure on the shifter?

You could have a bad shifter dog on second gear from years of abuse?

The transmission was rebuilt, new gears, sleeves, shift forks, anything that was questionable I had them replaced. I have taken the transmission to two other shops, both said it was fine. I have not tried putting pressure on the shifter because it does not come out of gear, or tries to.

When it was a stock 2 wheeler I did not have this problem. That's why I am stumped. Could the extra weight and the gear ratio be the problem?

[Jack Klarich]

The transmission was rebuilt, new gears, sleeves, shift forks, anything that was questionable I had them replaced. I have taken the transmission to two other shops, both said it was fine. I have not tried putting pressure on the shifter because it does not come out of gear, or tries to.

When it was a stock 2 wheeler I did not have this problem. That's why I am stumped. Could the extra weight and the gear ratio be the problem?

I dunno bout that

How is your primary chain adjustment?

Also final drive?

[don56]

I dunno bout that

How is your primary chain adjustment?

Also final drive?

Adjusted primary by factory manual, final chain has about 1/2" play.

[Jack Klarich]

Adjusted primary by factory manual, final chain has about 1/2" play.

Interesting, sounds like the engine has a miss @ the RPM in 2nd gear under load, what happens if you pull the clutch in and give it some gas does it wind up good? Is this a right side shifter?

[don56]

Interesting, sounds like the engine has a miss @ the RPM in 2nd gear under load, what happens if you pull the clutch in and give it some gas does it wind up good? Is this a right side shifter?

Bike is a right hand shift, has electronic ignition. I have by passed 2nd and gone right into 3rd just to see how the bike will react, it will pull up through the rpm range with no problems, it's a little sluggish at first, but it doesn't cut out or miss.

The ignition, could that be the problem? Could it be electric and not mechanical? If electrical why just 2nd gear?

[Lee H. Mann]

I mated a servi-car rear end to my 74 sportster, it has a weird issue with 2nd gear. Has anyone that has combined these two have any problems?

All gears work fine but when I'm in 2nd, the motor rpm's won't stay constant, it's as if I'm twisting the throttle back and forth, the bike jerks. Makes no difference what speed or rpm I'm at when I shift to 2nd the bike starts this jerking motion, the engine rpm's go up and down, I shift to 3rd and all is fine. It's not popping in and out of gear, it's like give it gas, stop, give it gas, stop, all the time while in 2nd.

I have tried different drive gears, it now has a 19 tooth sprocket, stock rear sprocket.

Any ideas?

Have you found the cause of your issues with 2nd gear ??

[Old Road Dog]

I think he needs a new clutch.

[Jack Klarich]

I think he needs a new clutch.

I dunno, the OP said it shifts fine into third and does not seem to slip

[don56]

Have you found the cause of your issues with 2nd gear ??

No I have not . I put a new clutch in about 50 miles ago. This problem did not show up until I turned it into a trike. This is why it's so frustrating. The rear end is an old mechanical brake set up from a servi-car, converted to disc brakes.

[George65]

No I have not . I put a new clutch in about 50 miles ago. This problem did not show up until I turned it into a trike. This is why it's so frustrating. The rear end is an old mechanical brake set up from a servi-car, converted to disc brakes.

Hi i,m new to this forum and maybe you can help. I,m up to get a rear-end of a servi-car an would like to do the same to my Ironhead but notice is on the left side and my Iron is on the right is it only a question of turning the axil 180 degress from left to right i don,t have it with me to chek before i buy your help and pics would be appreciated.Thks

[George65]

No I have not . I put a new clutch in about 50 miles ago. This problem did not show up until I turned it into a trike. This is why it's so frustrating. The rear end is an old mechanical brake set up from a servi-car, converted to disc brakes.

Chain binding have you tried lifting rear end and shifting thru gears with no weight on bike.!

[don56]

Chain binding have you tried lifting rear end and shifting thru gears with no weight on bike.!

No I have not, I am going to try that. Thanks for the idea.

[don56]

Hi i,m new to this forum and maybe you can help. I,m up to get a rear-end of a servi-car an would like to do the same to my Ironhead but notice is on the left side and my Iron is on the right is it only a question of turning the axil 180 degress from left to right i don,t have it with me to chek before i buy your help and pics would be appreciated.Thks

Sportsters and servi-car drive chains were both on right side.

[George65]

Sportsters and servi-car drive chains were both on right side.

Have only seen on pics seem to be to the left don,t know if its mech. or juice brakes.

[Jack Klarich]

Sportsters and servi-car drive chains were both on right side.

If I remember right all the 45 Flatheads were rs chain including the KH models

Guess that maybe why the MOCO left the Sportsters rs drive also

[don56]

No I have not, I am going to try that. Thanks for the idea.

I just put the bike on stands, it runs through all gears the same, no stumbling in second, no rpm change no lugging. Take bike off stands, go for a ride, go into second and it does it's jerking, and only in second. All chains are adjusted properly, new clutch, everything on this bike is new, all but the rear end. Any more ideas?

[Jack Klarich]

Did you change 2nd gear ratio with a new gear?

[George65]

I just put the bike on stands, it runs through all gears the same, no stumbling in second, no rpm change no lugging. Take bike off stands, go for a ride, go into second and it does it's jerking, and only in second. All chains are adjusted properly, new clutch, everything on this bike is new, all but the rear end. Any more ideas?

Try by loosing rear and primary a bit at a time up front is factory but rear isn,t maybe arc with some weight on it a couple of thousands of an inch can change the readings.!do you have any pics