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Messages - Cb750r
1
« on: April 02, 2024, 04:58:48 PM »
Practical advice for OP to check nothing simple is catching you out on this set.
No carbs should "hang" on the throttle pull cable at closed position. This is ONLY facilitated by throttle stop screw next to cylinder #4 in providing absolute slide base position. If there's any tightness in pull cable at this position, then it needs adjustment to provide slack such that it can't interfere with complete "drop" onto that stop when you just let the twistgrip go.
Make absolutely sure there's no conflict with secondary cable throughout full twistgrip movement. There's usually only adjustment on pull, with return being fixed.
You can remove the return cable while you try to diagnose fault, but advise to use when ultimately riding it though.
Idle mixture screws are set from a start point of 1 & 3/4 turns out from fully closed on the F carb set. Anything significant below that will likely give the symptoms described, effectively lean idle, with revs slowly drifting down and stalling. Make sure they are in the starting position if you don't know how they've been set.
Worth verification of these points to see if there's anything basic running you ragged.
Really good points, all round. I have a velocity stack/single foam filter setup on my 750 and I have it well sorted jetting wise, and I’m always pleasantly surprised how well it starts idles etc after a long winters nap. I’m a firm believer of a good fuel additive in the winter storage and first several tanks in the spring get a fuel system cleaner as well to help clear up and storage hiccups it’s developed. cable routing can play a big effect on the throttle sticking. Especially if you’ve changed bar type to be different than stock. I have taken a modern bicycle shift cable and unwound it to get individual strands of wire to help gently clean out jets. The individual strands are very fine and are quite good at piercing your skin so you’ll be encouraged to not use too much pressure!
2
« on: April 02, 2024, 06:26:40 AM »
The idle jets on these carbs are very small and lean, I’ve been through my PDs and made many jetting changes as I’ve owned my bike, to suit different air filters, and exhausts. I can take reference photos of my carbs if you’re going to work on them yourself. I’m in Canada so can’t help much beyond that.
I’d suggest start with the idle jets and confirm float heights if you’re going to work on them.
3
« on: March 27, 2024, 12:46:00 PM »
I finally received the rest of the correct Keihin brass from CMS yesterday. I got the carbs assembled and setup on the bench as close as i could get them synchronized.
As I suspected the previous owner put in some larger Jets and messed with the Needle position. There were #90 main Jets #44 slow and the needle clip was at the bottom groove. pulling the needle up to full rich. I replaced with #75 main #38 slow and clip in the middle position .
Took it out yesterday between showers. Wow what an amazing little bike. ran like a Swiss watch.
So glad to hear you sorted out the jetting! Congrats!
4
« on: March 26, 2024, 06:49:19 PM »
Good points about the BMW line up. My friends dad is a retired doctor has done what sounds like a few laps around North America on his big six cylinder BMW k1600.
And Laverdaroo, good to hear regarding the Vtec models. If you’re handy it’s not too bad for service costs it sounds.
Choices choices…
5
« on: March 26, 2024, 04:14:55 PM »
I’ve lusted after a vfr800i pre Vtec bike for a long time. It should be noted the Vtec models are supposedly expensive to service hence my desire for a 98-01 model. I owned a 93 VFR750 for a few years and it was just such a good bike. Heavy to transition but stable as a rock.
Have a friend with a sprint it’s a great long distance machine but it hasn’t weathered the test of time in the cosmetic department.
6
« on: March 25, 2024, 07:51:09 PM »
Picked up this shiny refurbished crank during lunch at the UPS depot.
Can’t wait to have this lightened and balanced beauty back inside the engine! Have a balanced stator rotor to install on the end which should make this one smoooth 836cc when put back together!
Hopefully all of my bearing clearances measure out well, and I can proceed with final assembly.
7
« on: March 24, 2024, 12:02:08 AM »
I believe I can let 1-2 of the tanks go eventually…
For me as a 46yr old, and these being pretty much the same age it’s fun. Plus these being the precursor to all of the inline 4 Supersport and superbikes of the 80’s and 90’s has always made me a fan of the 750F where as the older K1-6 are more “retro” in my eyes.
8
« on: March 23, 2024, 08:07:13 PM »
Is there a Canadian version of the phrase “ glutton for punishment “ ?
Sent from my iPhone using Tapatalk
Dad has expressed interest (has eyes on my 750), so hopefully we can make one of these his! Plus I kinda know these F2s pretty well. I might as well continue working on restoring some to running condition!
9
« on: March 23, 2024, 02:38:51 PM »
More F2’s to work on!
10
« on: March 11, 2024, 12:14:27 AM »
Ted that graph I sent you is from of one of the worlds largest oil additive packages manufacture. That graph shows differences to the specifications, and therefore the differences in the properties of the different oils.
You can get Volvo approved oils from a few sources. I sell Motul automotive oils in Canada and they have a factory approved product as attached. I’m sure as it’s a French company you can get it.
I’m sure there are several other options.
11
« on: March 10, 2024, 03:31:41 PM »
Ted, ebay item 303566439357
Sometimes comes up on special offer, way cheaper than local parts suppliers, i use it in the lexus rx mate
Bryan, was not calling you misleading, just the eBay post as it seems to list every oe specification imaginable in the photos, I also drive a Toyota, and a modern API SP, oe ILSAC gf6 is all the Toyota’s require in terms of specification.
12
« on: March 10, 2024, 03:27:19 PM »
Yep probably this stuff. https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/0FC452DB4251C88A802583450015AE03/$File/bpxe-anxbhg.pdf I work in the automotive parts business specifically for the Euro, and Asian brands of cars, I spend a lot of time discussing the right fluids for my customers needs. Late model Volvo’s usually have a unique oil specification and as far as I’m aware the mild hybrids call for that RBS0-2AE specification which as seen in the graph below has different properties vs a ‘normal’ ILSAC Gf6 0w20. It has different properties than GMs latest dexos1gen3 specification as well. I am just guessing as I don’t have year and specific model info but the xc40 mild hybrids are only a few years old now maybe 4 at the oldest I think. Maybe you got them sooner on that side of the pond. If your car is still under warranty I’d chose an oil that has that specification, so as to ensure your using an oil that will satisfy any warranty requirements on your engine should any issues arise.
13
« on: March 10, 2024, 06:50:43 AM »
Pretty sure that Volvo has a specification for the 0w20 to meet for that car beyond just 0w20. Volvo VCC RBS0-2AE 0W-20 synthetic oil Isn’t the same as a regular 0w20 for typical Asian cars or dexos1gen2 oils That eBay listing is misleading as the TDS sheet doesn’t include the Volvo approval. https://www.mannol.de/create-pdf/108/en
14
« on: March 07, 2024, 02:54:40 PM »
Pressed in my new bronze Swingarm bushings last night. Also took measurements for future reference, (aka I own a lathe and should’ve made these)
Recovering from Covid, progress in the shop and life was slowed to a crawl for a bit there. Glad to make a little forward progress…
15
« on: March 05, 2024, 11:19:28 PM »
Hi I know this is a side track for your thread, but as you have Laverda in your handle you might be have seen this or know where to look.
This is a photo of my friends dad as he helped in the pit crew for this bike in the early 70s in Canada, my friend is trying to track down the bike/current owner.
If you have any suggestions for him it would be appreciated.
Just noticed the bike is an SFC production racer, rare and expensive. JLO will likely know it's history and where it is now as there is a register of them. The frames on those were not painted but galvanized. A good mate of mine up in Scotland had one and he let me ride it for a couple of hours, absolutely fantastic, a true racer on the road. I know he sold it for £25k about 15 years ago and they are worth a lot more than that now. If the bike in your photo is a genuine Laverda endurance factory bike, name your price!
Thanks for the reply. I think he’s made contact with a person named Marnix on Facebook, but the other info and person may help. I see those bikes fetch top dollar! I can’t say I’m well versed in them.
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