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Discussion Starter · #1 ·
I wasn't really looking for another bike but I came across this one locally.
Its a early Yamaha XJR 1300.
55000 miles, Top end rebuilt 3000 miles ago. $6500 aud
A bit expensive but I couldn't build it for that.
What do you all think?
Tire Wheel Fuel tank Automotive fuel system Vehicle
Tire Wheel Fuel tank Automotive fuel system Vehicle
 

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This is what the seller says.
New Mikuni Flat side carbs, tuned and balanced Heads flowed Factory looking but completely modified exhaust Dyna 2000 high performance ignition module and coils Barnett heavy duty clutch kit installed Quick shift
Does it run great throughout or is he making excuses that it might need more tuning work?
 

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All that carburetor and engine intake work and expense and then they guy sticks cheap little paper pod filters on the mouth of each carburetor, he might as well run open carburetors which never really works good.
The 1300cc engine is hugely powerful so you're right, judging the engine performance is not easy, but fuel economy and consumption is still a good indicator if his modifications have improved performance or just made it eat more fuel.
Guessing he is not receptive to test rides and probably does not have a recent dyno test chart to show you.
 

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Discussion Starter · #8 ·
All that carburetor and engine intake work and expense and then they guy sticks cheap little paper pod filters on the mouth of each carburetor, he might as well run open carburetors which never really works good.
The 1300cc engine is hugely powerful so you're right, judging the engine performance is not easy, but fuel economy and consumption is still a good indicator if his modifications have improved performance or just made it eat more fuel.
Guessing he is not receptive to test rides and probably does not have a recent dyno test chart to show you.
I will go over tomorrow and try to sus it out.
Thanks
 

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Since it's a genuine Mikuni kit, I doubt that they would be $30 paper filters.
" Having to raise the carbs negates the use of the standard air-box, where there’s 4 cloth/paper dry type automotive pod filters included."
Dry paper air filter is nothing like an oiled K&N filter made from felt.
Mikunioz is a Mikuni distributor not the parent company.
 

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Yeah, I’d definitely swap those cheap pods for K&Ns (like are shown in the Mikuni catalog previously posted). At least the K&Ns don’t block the inlets and they do incorporate a funnel, of sorts, into their design.
 

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Oiled filters are near waterproof, filter better and serviceable. There is nothing stopping you from putting a large foam oiled cylindrical filter (with a flame screen) over any velocity stack stock or aftermarket and that will net you a much better air intake system. They sell 4 lengths of stack for those carbs alone just so you can tune it for the service needed.
Looks like it would be a nice sport touring ride from here :cool: with a few small upgrades.

... is that tiny cylindrical pod filter under the carbs the only vent for the crankcase? That would get changed immediately.
 

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Looks good and the price is reasonable for Oz market. Stick it on the dyno when you get it and see how well it runs. Then pull the filters off and run it like that back to back and see if the filters are a problem in terms of airflow.

Then get a set of RamAir foam filters or whatever brand you like and test them and see what's up.

But in terms of your question, yes go and buy it if you like it.
 

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:unsure: ever see an engine run great with an open carburetor? for sure it's going to run slightly better then one trying to breath through wet paper, but you're still missing the opportunity to tune the intake & I bet you get to see raw fuel spray at the mouth of the carburetors when it's running and you throttle up.
 

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Glad you asked. Of course wet soggy paper is not a viable option, but air filters rarely get very wet unless riding in a monsoon which Alex might experience sometimes.

I usually fit the air inlet velocity stack that comes with the carbs I am using. For example on a CB77 I use CB750 carbs and they have a nice long and well designed stack. On our 240cc CB160 race motor I used VM28s and found some stacks that work well.

On the dyno we tested with short and long stacks and wih no stacks and the difference was less than 1/2 a HP with the slightest tilit in the curve as expected. I prefer to smooth the air flow into the carb and on a GT750, we ran the CV carbs with UNI filters, stock air inlets and with special ultra short Lectron type stubby inlets and no discernable difference in rideability power or reversion.

Our TZ motors always run open. No stacks no filters, just open and the reversion can be seen at low revs with fuel stand off behind the carbs.

That's why I suggested that he run it on the dyno so he can see what that motor likes with those carbs. I would expect stacks to be best, followed by good large volume filters and then open carbs a little way behind. I am a big fan of well designed velocity stacks and IIRC when David Vizard tested them decades ago, a stack with slight taper and rounded intake flowed about 5% more than open and some flowed less than stock. Straight tube lost 6.7%, straight taper without a flare lost 5.5% and the best was Lectron style which added 5.8%. In that testing he found/proved that all that really matters is a radius on the intake end. Without a smooth intake, flow is disrupted.

On our old motors where we need every tiny poofteenth of power, that stuff matters. On a 1300cc behemoth i doubt that any of us here would notice the difference in power but driveability could be impacted.

That's why I suggest that if he buys it, he should find out for himself. he's a smart man and not afraid to try things that the rest of us are sure won't work. Sometimes they do and sometimes they don't.
 
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