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Old 08-29-2013, 09:29 AM   #1
Sniper X OP
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Swapping a /6 motor and trans into a /5 bike

Is it a direct swap? I sold my R60/5 to a mate in NYC and he found a cherry R75/6 motor with the 5 speed and wants to swap in the 75 motor and trans....
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Old 08-29-2013, 09:40 AM   #2
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I think so, others will chime in... but there will certainly be some wiring mods. Worth it, for the up-power while keeping the Slash 5 coolfactor....

Switchgear etc to remain Slash 5? Different starter relays, interlocks, turn signals etc, but all very do-able.



Keep the 60/5 for someone who want to "up" the mill from a Slash 2....!!
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Old 08-29-2013, 09:44 AM   #3
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Quote:
Originally Posted by bpeckm View Post
I think so, others will chime in... but there will certainly be some wiring mods. Worth it, for the up-power while keeping the Slash 5 coolfactor....

Switchgear etc to remain Slash 5? Different starter relays, interlocks, turn signals etc, but all very do-able.



Keep the 60/5 for someone who want to "up" the mill from a Slash 2....!!
The /5 motor only has about 40K original miles on it so is cherry. BUT he wants a 5th gear....not even concerned about the power aspect. Can ya just swap in a /6 trans for the /4 4 speed?
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Old 08-29-2013, 09:58 AM   #4
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Definite yes to the tranny, the only limitation there is that the later clutch "assembly" used a different-length input shaft, but that was post Slash 7 iirc. Heavy-flywheel clutches were the same on /5 and /6's.

He would probably also lose the kickstart, (though some 5-speeds have a kicker) ....the /5 kickstart was considered a "use only if necessary" item, not up to day-to-day starting over the years.

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Old 08-29-2013, 10:04 AM   #5
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/6 5 sp gearbox had it's own set of problems

Does the /6 gearbox have a kickstarter?? The /6 5 sp from 1974 had problems with the kickstart gear breaking and was kinda weak in the beginning. The 4 sp gearbox he has currently is very solid, but if he is looking for 5th gear then yes this should be as easy swap.


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Old 08-29-2013, 10:27 AM   #6
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A 1975 or 1976 R75/6 is a good candidate for a direct swap into any /5 bike. The wiring stays on the frame so you are using the wiring of the /5. Any /6 transmission will fit the original R60/5 engine and frame. The R75 engine tho is a much better engine than an R60.

What is not always a good trade is getting a 1974 5 speed weather it is with the bigger engine or not. The 1974 5 speed is a troubled transmission most of the time. There are bikes on the road and they have many miles with this transmission but the fact is you are taking a chance on possibly getting a Lemon if you get a 1974 5 speed. I advise and many others agree, steer clear of the first year 5 speed with the kick starter.

If it works you may be able to sell it for enough to off set the cost of parts that work better. There are riders that want these pieces and know the problems but for the majority of riders steering clear of a 1974 trans is good advice.

The 1974 5 speed has a smooth case and a kick starter. It was generally the only year that had a kick starter until later when it was brought back for some of the GS bikes. All trans have the reinforced case after 1979 so beware of any smooth case with a kicker.

If you end up with a spare R60/5 engine you should be able to sell that pretty fast also. I still think the R75/6 is better though.
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Old 08-29-2013, 10:36 AM   #7
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Quote:
Originally Posted by disston View Post
A 1975 or 1976 R75/6 is a good candidate for a direct swap into any /5 bike. The wiring stays on the frame so you are using the wiring of the /5. Any /6 transmission will fit the original R60/5 engine and frame. The R75 engine tho is a much better engine than an R60.

What is not always a good trade is getting a 1974 5 speed weather it is with the bigger engine or not. The 1974 5 speed is a troubled transmission most of the time. There are bikes on the road and they have many miles with this transmission but the fact is you are taking a chance on possibly getting a Lemon if you get a 1974 5 speed. I advise and many others agree, steer clear of the first year 5 speed with the kick starter.

If it works you may be able to sell it for enough to off set the cost of parts that work better. There are riders that want these pieces and know the problems but for the majority of riders steering clear of a 1974 trans is good advice.

The 1974 5 speed has a smooth case and a kick starter. It was generally the only year that had a kick starter until later when it was brought back for some of the GS bikes. All trans have the reinforced case after 1979 so beware of any smooth case with a kicker.

If you end up with a spare R60/5 engine you should be able to sell that pretty fast also. I still think the R75/6 is better though.
The kickstart continued as an option on the 5 speed. Some ordered it new, many others retrofitted it.
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Old 08-29-2013, 10:42 AM   #8
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Originally Posted by Plaka View Post
The kickstart continued as an option on the 5 speed. Some ordered it new, many others retrofitted it.
Yes it was an option, I forgot to mention that. But it is my understanding that so few opted for the kick starter that it is as rare as teeth on a chicken? Or have you seen many?
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Old 08-29-2013, 11:03 AM   #9
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My /5 has a /7 engine, 100S actually. I put it in there about twenty years ago. It went in there like the engineers meant for it to. There's really nothing to it. I think the alternator has one more positive lead which IIRC runs from the stator to the starter relay, or maybe just straight to the battery. I can't remember for sure, but it's a big nothing. One look at the wiring schematic for the /6, and you'll see where it wants to go. Oh, one other thing I can think of, which could be a deal breaker. You'll have to crimp on a female spade terminal on the neutral light lead. For what it's worth, probably not much, I actually prefer the four speed trans to the 5 speed I originally put in it when I swapped it all over. Does the /6 engine come with carbs? R60 carbs won't do on an R75.
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Old 08-29-2013, 11:25 AM   #10
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Originally Posted by JonnyCash View Post
My /5 has a /7 engine, 100S actually. I put it in there about twenty years ago. It went in there like the engineers meant for it to. There's really nothing to it. I think the alternator has one more positive lead which IIRC runs from the stator to the starter relay, or maybe just straight to the battery. I can't remember for sure, but it's a big nothing. One look at the wiring schematic for the /6, and you'll see where it wants to go. Oh, one other thing I can think of, which could be a deal breaker. You'll have to crimp on a female spade terminal on the neutral light lead. For what it's worth, probably not much, I actually prefer the four speed trans to the 5 speed I originally put in it when I swapped it all over. Does the /6 engine come with carbs? R60 carbs won't do on an R75.
if he did an R75 motor trans he would get the carbys as well.
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Old 08-29-2013, 12:02 PM   #11
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Yes it was an option, I forgot to mention that. But it is my understanding that so few opted for the kick starter that it is as rare as teeth on a chicken? Or have you seen many?
What I have seen is dependent on the circles I have run in. So if I say "many" or "few" it doesn't mean much w/o a context or back ground.
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Old 08-29-2013, 01:20 PM   #12
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Originally Posted by JonnyCash View Post
I actually prefer the four speed trans to the 5 speed I originally put in it when I swapped it all over.
Why's that?
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Old 08-29-2013, 03:00 PM   #13
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I don't know if I am trying to answer the question above "why is that".... but the 4- and 5-speed transmissions both have the same top gear. So 4th on the 5 speed is a very close-ratio to the 5th, and doesn't give longer legs.

There is probably some technical reason in how the transmissions are built that would explain why some prefer the 4 speed, but I will let them talk about that!!

If you are curious, you can look at the gear-ratios and speeds on Antons website, it will show you the relative gearing for each transmission. (Sorry, I am not savvy enough to get it to save that interactive page so that I could print and save it.....)

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Old 08-29-2013, 03:43 PM   #14
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I prefer the four speed to the five, because airheads aren't peaky engines with narrow power bands, and the four ratios, I feel, are plenty to keep the engine in the sweet spot.If I were racing, it would be different, but I ride my /5 swiftly and smoothly, but not aggressively. It just doesn't encourage that riding style, in my opinion. I would like, someday, to put the five speed back in, with the extra tall fifth gear that is available, as even though I have a 33/11 rear, the bike would happily pull a taller gear. Furthermore, the four speed feels to me like the tougher transmission, and the kick starter is not known to be fragile. I'm not trying to convert anyone here, I just ,for now at least, prefer it.
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Old 08-29-2013, 03:58 PM   #15
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4spds are tough and have the same top gear ratio as the 5spd.

5spds offer a bit more flexibility: Down-shifting to 4th for passing isn't as dramatic/traumatic as down-shifting to 3rd on the 4spd, which is a major ordeal with a 9 to 12lb flywheel, depending on the year of the motor.

I'd want more(taller) final drive gears if I'm putting an R75 motor in an R60. At least a 3.20:1.

imho, ymmv, fwiw etc.

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