Project "walrus" Yam XS 750

Here are some pics...carb tops say mikuni...hope that those mkII's....
Edit:looks like they are generation 1 mikunis.
 

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Should i throw them too into the bin :)?

Just found that....
Will these fit my XS?what will I need to modify to fit these?
 

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Yep Mk1
A lot cheaper to clean and new mounting rubbers than spend Euro199!
You are going to need new mounting rubbers no matter what carbi you have on it. I my humble opinion get the mounting rubbers and see how it runs. You are going to need to rejet the Triumph carbies before you even get started!!!
 
Re: Project "walrus" Yam XS 750

Thanks tim!

Just finished cleaning my mk1 carbs lets see what they will do...i will set the mixture screws to 1 1/2 turns out for starters.

Just figured today that i have mk2 carbs on my parts bike...when i opened the carbs they were nice and clean but two posts where the floats are fixed were broken off...so i guess they are paperweights now.
 

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Re: Project "walrus" Yam XS 750

What a shit!!!
The PO must of used a hammer to get the float pins out!
From the repair manual, for carbs with 145 main and 17.5 pilot the float height should be 26.6mm and pilot air screws at 2 1/4. Does it have an aircleaner? Should start though but if the mounting boots are buggered and you don't have an aircleaner it is going to be lean.
Good luck
Tim

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Re: Project "walrus" Yam XS 750

XS750AU said:
Yep Mk1
A lot cheaper to clean and new mounting rubbers than spend Euro199!
You are going to need new mounting rubbers no matter what carbi you have on it. I my humble opinion get the mounting rubbers and see how it runs. You are going to need to rejet the Triumph carbies before you even get started!!!
The bike runs so much smoother and better with those carbs, i believe its a justified investment. I also think the daytonas power figures are resembling the xs, a bit higher of course. May just need a different main and 1 needle shim.

Ryan Stecken said:
Thanks tim!

Just finished cleaning my mk1 carbs lets see what they will do...i will set the mixture screws to 1 1/2 turns out for starters.

Just figured today that i have mk2 carbs on my parts bike...when i opened the carbs they were nice and clean but two posts where the floats are fixed were broken off...so i guess they are paperweights now.

I welded up a float post i broke on my ladys xs1100, they break too easy even if you do it the right way. Was good as new afterwards though, you cant even see its been broken. Kintsukuroi as the japanese say.
 
If you can find someone to weld them for not much, then they would be great. If they want to charge shop rates then might be better getting the Triumph carbies.
Just check that the pitch and mounting boss on the engine side matches the mounting rubber boot internal diameter on the triumph carbies.
I am using a triumph 1050 header on the 896 and the pitch was perfect, but the head interface needs work to make it fit. The triumph carbies Dave used were a simple fitment. Was that correct Dave?
It should run OK on the Mk 1 carbies, at least to see if the rest is OK.
Cheers
Tim
 
Hey guys...so today i tried to start the xs with the freshly cleaned carbies (mikuni 1).
Checked for spark and cylinder 1 has no spark,cyl 2 weak spark and cyl 3 strong spark.
It kinda ran on 2 cyl but only when I was holding onto the throttle.
The PO told me that the regulator unit might be shot,could this cause this issue?
Could it be some shot coils?

Red white and orange goes to the coil i checked for continuity to the ignition box the cables are fine.
Checked for volts coming out of the box...no volts on red white and orange.shot ignition box?

I also opened the oil cap of the motor and tried to move the main chain and I could move it up all the way to the motor lid...looks like theres a lot to do on that thing...


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Re: Project "walrus" Yam XS 750

Thanks man!any ideas on my last post (spark problems)?

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Re: Project "walrus" Yam XS 750

XS750AU said:
If you can find someone to weld them for not much, then they would be great. If they want to charge shop rates then might be better getting the Triumph carbies.
Just check that the pitch and mounting boss on the engine side matches the mounting rubber boot internal diameter on the triumph carbies.
I am using a triumph 1050 header on the 896 and the pitch was perfect, but the head interface needs work to make it fit. The triumph carbies Dave used were a simple fitment. Was that correct Dave?
It should run OK on the Mk 1 carbies, at least to see if the rest is OK.
Cheers
Tim
It was very straightforward, bolts straight on to the stock rubbers.
 
Re: Project "walrus" Yam XS 750

Any ideas on my spark problem data?

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Hi Ryan
If you have good spark on one cylinder then it is unlikely to be the CDI unit. Each cylinder has its own coil and high tension lead. My 750 was week on #1 and it was the high tension lead. If you have some spare leads and coils on the other bike, then start by swapping the lead. If still no good try swapping the coil the coil.
See where that get you.
Regards
Tim
 
Re: Project "walrus" Yam XS 750

Hey tim thank you!
By lead you mean the thick cables coming from the coil going to the spark plug boot dont you?

What do you say concerning the main chain slack i described?

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Ryan
For testing make sure the battery is fully charged. My harness was cactus and the bike was not charging. When the battery lost charge the engine started to miss on one cylinder and as the charge dropped it would not run at all. It could be the regulator if the battery is low. If your battery is fully charged then keep going with the high tension leads and coils.
To test the regulator you should be getting a voltage better than 14volts across the black and red wire coming out of the regulator.
Good luck
Tim
 
Ryan
Yes cables coming out of the coil and going to spark plugs - the caps can also be faulty and leak the spark!!!
The chain you can see through the oil cap is the primary chain which transfers power from the crank to the clutch - they are a known weak point. Many people on line make up chain tensioners to "fix" the problem. The good point is that on the XS750 they are bloody easy to take the side covers off and fit a new chain as it is on the side of the engine. You can change the chain without removing the engine from the frame ;D. All the 4 cylinder engines have the primary chain going through the middle cylinders. and are a lot more work :mad:.
Sounds like it has a bit of slack, but they are never "tight". The top is the tension side when driven and the slack is down at the bottom where there is a little extra room. If you are not finding aluminium filings in the engine oil then it is not hitting anything and it is not you top priority. It can wait until you are ready to change it - they are relatively expensive.
Good luck.
Tim
 
Re: Project "walrus" Yam XS 750

Thanks tim!i guess then i will get new plug caps in combo with the new leads.
How are the leads mounted in the coils?

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Ryan
You need to take the screw cap off the old cable and put it on the new cable. Then there should be a metal screw thread poking out of the coil that you screw into the wire on the new lead. Then you screw the cap down on the coil to clamp it all tight.
I take it that your battery was fully charged?
Cheers
Tim
 
Re: Project "walrus" Yam XS 750

Ok tim!
The battery read 12.3Volts without the starter running,i guess it needs a good charge since I already tried to start it a few times (battery is new).

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