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XV750 cams in an XV920 ? (Read 747 times)
Odradek
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Bike: XV920R
XV750 cams in an XV920 ?
26.04.24 at 18:35:28
 
I have a 1982 XV920R, (US model), and it has seized camshafts.
The parts are available, but expensive.

However there are options available on eBay.

Early XV750 has the same part numbers for camshafts as the XV920, (4X71217101 & 4X71218101) but later models have a different part number, (42X1217100 & 42X1218100).
Does anyone know if they are the same part, just with a new number ?

Are the cams from a TR-1 the same ?

Just trying to see what will fit.

Also, I've read that XV750 heads are a straight saw for 920 heads, and give a higher compression ratio.
Is it a simple straight swap ?

Thanks for any info.


Also, as far as I can work out, the TR-1 camshafts are 4X71217100 and 4X71218100.
Can these be used in an XV920R ?    





 
« Last Edit: 26.04.24 at 20:57:27 by Odradek »  

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Odradek
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Posts: 25

Bike: XV920R
Re: XV750 cams in an XV920 ?
Reply #1 - 26.04.24 at 23:35:06
 
Answering my own question, but there seem to be two different answers in this old thread I've found...

Quote from patricks on 15.10.19 at 21:33:00:
Cylinder heads BT1100, TR1, XV920r: all the same size of inlet and outlet valves

Camshaft lift: all the same cam lift

Timing: TR1 and XV920r same timing (longer than BT1100), BT1100 shorter timing


And then this reply from Nanno...
Quote from nanno on 10.10.19 at 19:24:54:
They interchange, but they are not the same. XV920 should have the tallest lobes. BT1100 will have slightly milder timing and smaller lobes. XV1000 and XV1100 will have the same timing as the 920, but slightly smaller lobes.


So what would be the result of installing TR-1 camshafts in an XV920R ?

Hoping to make a decision by tomorrow, as I've found some TR-1 cams for sale.


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nanno
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ned ganz so
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Re: XV750 cams in an XV920 ?
Reply #2 - 27.04.24 at 07:45:10
 
It doesn't matter - TR1 and XV920R are the same camshaft, with the same base-circle. The main benefit of e.g. TR1/920 cams over later ones, like LATE XV1000 or XV1100 cams is the fact that you can have them reground for more lift. If you don't plan to do this, whether you go with an XV700, 750, 920, 981(1000) or XV1100 cam will not make the slightest difference to you. When you come to the V-star stuff (BT1100/XVS1100) things change as these have a different lobe separation angle.

Hope this clears it up.

Cheers,
Greg

 
 

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Odradek
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Bike: XV920R
Re: XV750 cams in an XV920 ?
Reply #3 - 27.04.24 at 09:34:00
 
Many thanks !

I've found some complete heads for sale on eBay, which would save a huge amount of money over buying new XV920 cams and rockers.

There's a choice of 1986 XV1000 heads and or 1985 TR-1 heads.


 
 

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Anja-D
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Bike: 1981 TR1. (5A8), modified with XV1100 (3LP) Eng.
Re: XV750 cams in an XV920 ?
Reply #4 - 27.04.24 at 11:12:22
 
Hey Odradek,
here some tech Infos. See the images.

The more jounger Models contain Camshafts with an other Diameter of the inner Bearing  (25mm instead of 24mm).
You  see it on the images

Best regards Anja

ADD:
Today I had removed my Camshafts. Unfortunately the END-Bearing-Diameter is 24mm on my XV1100, J.oP. 1989
So, the early XV1100 3LP my got the standard TR1 Camshafts. The later Production XV1100 got the Diameter of 25 mm, according the data sheets abbow.

 5A8_Camshaft_DIM_1.jpg   3LP_Camshaft_DIM_1.jpg     Pictures below may be scaled. Click links or pictures for original size Click here for all attachments  
« Last Edit: 29.04.24 at 22:21:12 by Anja-D »  

5A8_Camshaft_DIM_1.jpg
3LP_Camshaft_DIM_1.jpg

TR1 seit 1982, die aktuelle seit 1988, schraube und fahre selbst
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Odradek
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Posts: 25

Bike: XV920R
Re: XV750 cams in an XV920 ?
Reply #5 - 01.05.24 at 21:46:09
 
Thank you for all the info.

I have bought cylinder heads from a 1986 XV1000, and they have just arrived.
Fingers crossed that all is good inside.

One thing that threw me a little is that the oil baffle is on the front head and not the rear head like my XV920.
At what point did Yamaha switch that ?

 
 

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Anja-D
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Bike: 1981 TR1. (5A8), modified with XV1100 (3LP) Eng.
Re: XV750 cams in an XV920 ?
Reply #6 - 02.05.24 at 04:39:26
 
Hello, Odradek,
don´t worry about. The Oil baffle disk is mounted to that Camshaft where the Breather is lockated.
On TR1 the Breather is mounted to Cylinder head of  Cyl 2 (front). Here the Breather pipe ended in Inlet manifold for Cyl. No 1 Carburretor.

On some Models like your XV920 the Breather was placed on Cyl 1 (rear) and the Breather Pipe was led to the Cassis Frame. Sees Pic.

It is easy to change it. Just replace the Oil baffle to the rear Cylinder after install the Cylinderhead.
AND if your "new" Clinder Heads where delivered WITH Camshafts. Check it out whether the correct Camshaft is intalled to the Cyl-Heads where they belong to. (Cyl 1 Camshaft No1;  a.s.o.)

Best Regards
Anja

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TR1 seit 1982, die aktuelle seit 1988, schraube und fahre selbst
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