Yoshimura GS750/1000 2V Cam specs / catalog?

[Chuck78]

Does anyone have an old Yoshi catalog they could scan to give lift and duration/timing specs on GS1000/750 8 valve camshafts?

I'm wanting to install a set that measure roughly .353" or .354" intake and exhaust (no v-blocks to check exact lift currently), but would like to know the duration before I get these and install them in my build.

I missed a deal a while back on some Yoshi road and track gs1000 cams for $300 and am still kicking mysekf. They were around .374" intake and .354" exhaust, which the exhaust I saw was the same lift as the advertised cb750 isle of man Yoshi cam spec. GS # 's would be good. All I can find are cb750 complete lineup numbers, and gs1100e stage 1 and stage 2 numbers.
Neither seem to be the same lobes as the gs1000 cams I keep stumbling across.

Thanks

Chuck in Ohio

[GregT]

gs750001_zps995a3f17.jpgThis was i think, posted here some time back.

[Chuck78]

This was i think,

That one comes up pretty readily with a Google search, but since it says "SUZ GS 750, 1100" - I figured it was for the TSCC 16V (4V/Cyl) engines. Was this not the case?

If it were for a 2v (8v) engine, it would say "SUZ GS 750/1000" I would assume, as it's unlikely theY would advertise the cams for a 750 2v and an 1100G 2v without the flagship model GS1000 2v.



That's the Stage 1 cam, the Stage 2 cam card also was posted.

I'd love to see cam cards like that for the gs1000 etc cams.... or a catalog. I think BadBillyB had mentioned having some of this literature, but I haven't received a reply to the pm I sent him. Others have mentioned Yoshi catalogs on here, but due to the "your-account-gets-deleted-after-6-months-of-inactivity" policy, they are all listed as guest posts with no way to contact them...

[Chuck78]

Re: Cam degreeing

Just spoke to yosh...they had two spec sheets taped to the side of a filing cabinet in the back of the warehouse. Got lucky there.

Was told aside from that there is 0 information available due to the cams being so old, and POPY vs Yoshimura. Will post the spec sheets when I get them in my email for future searchers.

This is from:

http://www.gtamotorcycle.com/vbforum/showthread.php?175373-Cam-degreeing

[storm 64]

Hey Chuck, I'll call my brother and see if he still has his cam spec card...

[Chuck78]

That would be awesome! Even if not the same cam, it will give me a better idea of the yoshimura recommended valve clearances. I suspect they are different between a shim/bucket setup vs a rocker arm dohc setup. And different for race vs street use, and different for lumpy big lift vs slightly more than stock lift...

[Chuck78]

SOHC CB750 Yoshimura cam specs from Satanic Mechanic's site copied below.
the GS1000 "POP Y" Yoshimura camshaft measured lifts I have come across don't quite jive with these, but these are for reference at least:

http://www.satanicmechanic.org/yoshicam.shtml

Yoshimura Road & Track cam specs:
Int .378" 252° @ .040"
Exh .341 244° @ .040"
Int open 20°btc/close 52°abc
Exh open 46° bbc/18°atc
.004" running clearance (.006" race)

Yoshimura Isle Of Man cam specs:
Int .354" 264° @ .040"
Exh .337" 263° @ .040"
Int open 27°btc/close 57°abc
Exh open 56° bbc/27°atc
.004" running clearance (.006" race)
Must use Yoshimura valve springs


Durat In o/c Run-
Valve ion Lobe Ex o/c ning
Cam Lift @.04" center btc/abc clrnc
inches degr degr Description and Application bbc/atc inches
-------------------------------------------------------------------------------
Daytona Race.392 256 23/53 .004
.360 256 53/23 .004
Must use Yoshimura valve springs
-------------------------------------------------------------------------------
Road & .378 252 20/52 .004
Track .341 244 46/18 .004
-------------------------------------------------------------------------------
Stage 1 .362 253 105 21.5/51.5 .006
.330 244 105 47/17 .006
-------------------------------------------------------------------------------
Stage 2 .383 256 105 23/53 .006
.339 256 105 53/23 .006
-------------------------------------------------------------------------------
Isle Of Man Race .354 264 27/57 .004
.337 56/27 .004
Must use Yoshimura valve springs
-------------------------------------------------------------------------------
For racing applications, add .002" clearance



From a CB forum post:
Isle of man cam specs-In opens 27BTDC-closes 57ABDC lift 9.00mm
Ex opens 56BBDC-closes 27ATDC lift 8.55mm yoshi part# YH600-122-00
Valve clearance street-0.10mm race-0.15mm, ign timing +5 advance
Spring used was S+W I dont think they are available anymore yoshi
part# YH500-321-00, do not use stock springs with this cam, for
performance spring kit try www.webcamshafts.com,the isle of man cam
will fit the 500+550,hope this is of help
Cheers Kevin

[Chuck78]

Of those specs, the Road and Track profile and Isle of Man profiles seem to be the hot ticket for what I'm looking for. I don't want to lose the aggressive exhaust sound that the stock wide duration early GS750 (& 550&400/425) cams give. These 2 Yoshi POP Y grinds boost the lift and intake duration a good bit over stock, while keeping similar or slightly higher exhaust durations vs the stock gs750 cam. The 1000/850 GS stock cams had slightly less duration and slightly more lift than the 750, fyi. Suzuki engineers trying to boost midrange torque...

BadBillyB steered me in the right direction in another thread, basically pointed out what Yoshimura was accomplishing, and that a mix and match of 2 megacycle cams profiles ends up as basically the same as the Yoshi Road and Track specs listed from the CB750 site :

The .380 lift Megacycle cams seem to be the best choice if it were me. Might even consider mix and match, and use the .380 lift on the intake and the .354 on the exhaust. The megacycle 381-00 exhaust cam is slightly less duration. This will give you more punch at lower rpm's....An exhaust valve only needs to be opened so far to perform. Most cam sets are "cookie cutters", meaning they are the same except for the tach drive.

From the Megacycle Cams catalog:

Grind # 381-70
.380" lift
261° duration @ .040"
107.5° intake lobe center
108.5° exhaust lobe center
23 btc/58 abc.004" INTAKE OPEN/CLOSE
59 bbc/22 atc.004" EXHAUST OPEN/CLOSE
.004" running valve clearance
All around road & road race performance. Top-end power. Use spring kit. Stock pistons OK in 1000cc, must use modified pistons in 750 and 850.
Same grind for the gs550/650 says:
Best all around street/road performance. Use modified pistons and springs. Mid-range and some added top-end power increase.


Megacycle Grind #381-00
.354" lift
254° duration @ .040"
110° lobe centers
17 btc/57 abc 57 bbc/17 atc
.006" intake .008" exhaust running clearances

OK with stock pistons and springs in 850/1000, must check 750. Increased mid-range power.

[Chuck78]

More Honda CB forums info:

Sounds like you have an old Pops Yoshimura cam for a CB750 K.

The YR1-1 was called the "Daytona Cam" which is a flat-out racing grind and peaks @ around 9,500 RPM.

The YR1-2 was the mild version and was called the "Road and Track cam", this was a popular grind back in the day when used with the Yoshimura 812 piston kit.

I don't have any specs for either one of them.

My Daytona cam is REALLY nice once it gets above 7000 rpms all the way up to 10,000 rpms. It'll run through my 8500 redline and back into the blue area in about half a heartbeat. Kinda doggish at lower rpms. It gets it's name from the Daytona 200. Not likely those engines went below 7000 rpm on that big long track.

I have 1 more piece of info at home that has the timing specs on it so you'll know how much advance to use. I think it's +5 over stock. I know I punched a new timing mark just past the T1-4 mark.

Info from the book GS1000 Preformance Portfolio

The Yoshimura superbike cams Int open 26 deg BTDC closes 56 deg ABDC ex opens 56 deg BBDC closes 26 deg ATDC Int lift 10.4mm ex lift 9.7mm clearance .005 in

^^^ That's 262 degrees duration (@1mm/.040" lift?) And .410" intake lift .382" exhaust lift for the Yoshimura team road race bike or Stage 3 cams I assume

Maybe this will help you. I just happen to have a Yoshimurs R&D catalog from back in 1980 that states....verbatim from the catalog....... "StageII cams (Bonneville etc.) are beyond stageI specifications and are best suited for racing applications. These cams offer a phenomenal increase in horsepower and torque in the middle to high RPM range. We recommend these cams for racetrack use only, however, a great many riders are using them on the street and enjoying the superior top end power. Once again a YOSHIMURA valve spring set is a must. Serious road racing applications require the use of an under-the-tappet shims (kit 1600-1602)"

......No specs are given though...... Then they go on to say that with the StageIII cams the lightweight tappet set is mandatory...... The buckets are a bit pricey, but I would highly recommend them if you like to twist the throttle hard......BadBillyB

[Chuck78]

Here's some info on the TSCC cams. I am wondering if that book SUZUKI GS1000 PERFORMANCE PORTFOLIO 1978-1981 has any further cam specs in it? Apparently is has all sorts of info on specials, performance data, mods, and performance parts. Might buy a copy myself.

Not sure if these are the current TSCC 750/1100E Yoshi cam specs, the POP Y era cam specs, or any in between 1978 & present:

Here is what I got. A gs/yosh guru sent it to me

STAGE I
Marked sux101 for Gsx 750/110016 valve-In;opens 20degrees BTDC closes at 50 degrees AbDC Lift .318/ 7.95 250 degrees of duration. Ex opens 50 degreesBBDC and closes at 20 degrees ATDC .318/ 7.95 + or - 2 degrees. 250 duration also . Running clearance is .06mm-.13mm.This is measured at 0.40 valve lift with 0 lash when you degree the cams.

STAGE II
Stage 2 are as follows ; Degreeing is the same specs as stage 1 .366/9.14mm intake and ex.366/ 9.14mm 250 duration also . All readings taken at 0.40 valve lift at 0 lash . Stage 2 rerquires the intake and exhaust guides to be shortened 1 mm for seal clearence . After mkt guides are usually relocated for you and after market pistons too for valve pocket clearance.

I believe that was a typo and should read @ .040" (1mm), not .40" (nearly half an inch).

[Chuck78]

Cool 1981 Yoshi magazine ad (Cycle World magazine I believe):

[Chuck78]

The mail carrier brought huge smiles my way today... smoking deal that I couldn't pass up was even better than I expected with original packaging included! 260 degrees duration @ 1mm (.040") lift spec (calculated off the timing figures listed) on the Yoshi packaging! The original packaging was a huge bonus. Paul the seller told me they were .353" lift approximately. I have not measured yet. I'm very excited to say the least. 260@.040 is a bit on the hot street side, but I could degree it in for more midrange. It will be a great match for the Rickman build, as that will be the real hot rid bike, although most bikes I would choose to ride turn into a hot rod as soon as I jump on em!



Now if I can just get my buddy Grant to buy a GS750 that he may repair and resell, so that I can buy the Yoshi series 1 exhaust off of it and swap on a MAC/Kerker in its place for him...

[Chuck78]

Yoshimura part# S07-111
IN 25* ~ 55* @ 1mm
EX 55* ~ 25* @ 1mm
.353" lift according to seller's calipers (v-blocks and dial indicator would be more accurate, the CB750 specs list .354" lobe as the Isle of Man cam intake lobe height so I think this may be that.



These have 3 boxes and none of them are checked (maybe the ink wore off?):
Cam-shaft: [road special] [road & track] [special racing]

Inked on are:
"TAPPET INLET + EXHAUST
6 ~ 8 THOU" (handwritten in ink pen)

I missed out on a $300 set of Road & Track spec Yoshi cams from Suzuki Performance Spares, they were .378" intake and .354" exhaust. I was very angry at myself for missing out on those.... $ was tight, then when I had $ to spare, a vintage pair of Fox Factory Shox was waved under my nose, & the Yosh R&T gs1000 cams sold...

[bobtail84]

I have been looking for right info to dial in my cams.. A pair of yoshi in.374 ex.354 cams.



I was the cheeky so and so that bought the cams from Nick Pepper @ Suzuki Performance Spares but they were the last piece in my engine build.

I have a very nicely ported head, wiseco 1085 BB kit all ready fitted, APE valve springs, welded crank , 33mm mikuni smooth-bores and a few other mods but the degree info was what I needed. I still have to fit the salty_monk front break kit so I can stop the old girl when she gets going but the engine is 3/4 done.

Jeff

[Chuck78]

Ahhhh darnit how I wish I had gotten a hold of those cams before they sold! Happy to see they went to another devout member of the GS Resources brethren however!

Megacycle has .380" & .354" grinds that if mixed and matched would very closely resemble the Yoshi Road and Track specs. Very nice street cams they make!