GS400/500 Gr650 Hybrid engine

[Rensdw]

Thank you all for the replies, I'm sorry it took so long; we were kind of busy here at work.
I send the crankcase out to a professional welder and he advised me not to weld it, it softens and warps the aluminium too much.
So he made me some plugs and reworked the mating surface, and I re-drilled the holes.



Then all the holes were taped (M10 x 1.25), next time; I will do this with the mill, and not by hand.......



Cylinder Fits





Of course the crankcase and cylinder don't match up, I'm going too feed the oil to the head externally.



Head fits too





These Allen screws will be replaced by 45 degree AN fittings





There are four oil passages (from crankcase to head), all through the outer stud holes and they split up, one small passage goes to the camshaft bearing, and the bigger passage goes to the valve bucket cavity.
Because the GS400x crankcase had only two oil passages going up the cilinder only two out of four valves/bearings get lubricated.
My solution is to run external aluminium lines and bypass the studs altogether, an update on this will come soon.

Next step is to get all my calculations right; Static and dynamic CR, Rod length etc. and then send out my crankshaft for a nice overhaul and rod change.
Also I have to figure out what to do with the chain tensioner because none of them fit like how they are originally.

[Rensdw]

I did some measurements today.

I saw some people on the net being sceptical about the gs400 60mm stroke, this confused me so I measured it; it really is 60mm

GR650 combustion chamber volume is 47CC.
GR650 Piston dome is 9.43CC
GR650 Piston pin to deck height is aprx. 18mm
GR650 Piston Wrist Pin is 18mm

GS400 Piston Wrist pin is 16mm
GS500 cilinder on GS400X bottom end without gaskets is aprx. 16mm wrist pin to cil. deck height.

The GR650 piston at 0 deck depth will be good for a CR of 8.4:1 with stock dome, so I will need custom pistons (Wiseco)
The new conrods need to be 1 to 1.5mm shorter, to get to 0 piston deck to cil. deck clearance I will need to play around with different gaskets.

Request for parts
Also I am looking for the GS500 oil pump drive gear, not the actual gear that is on the pump but the gear that drives the pump, there is one brand new on e-bay but it has to come from Israel.
The GS500 oil pump had a higher gear ratio which will help me to get the oil pressure up a little bit, I will be installing an adjustable oil bypass valve to set the pressure at a certain value.

[Rensdw]

Can one of the moderators move this thread to Performance/Tuning/Mods, I think that is a better place for this thread.

Finished one side of the cilinder head, one AN number 3 90-degree fitting, the tee-fitting will be capped off, can be used to connect an oil press. indicator.

[GregT]

You've just hit the snag to this combination. You really need the 18mm gudgeon pin for the big pistons but the roller bearing crank rods are 16mm...
So it's either custom pistons or custom rods.
Custom rods will involve fresh roller bearing big end bearings and will all depend on the condition of the crankpins when it's split...And will not be cheap...
Been there with custom Carillos for a 450 Honda, wanted to get away from the odd size rollers in the honda bearing, not cheap...
Whoever does the pistons will tell you that they don't like 16mm pins in that bore size either...

Oil pump gears - you don't want or need the pressure of the GS500. You've got a roller bottom end which lives happily on very low pressure. It is possible, I haven't tried it, that the GS750 16V oil pump gears used to increase pressure in the fours may fit the twins too. They offer a useful increase without going over the top.

[Chuck78]

GR650 combustion chamber volume is 47CC.
GR650 Piston dome is 9.43CC
GR650 Piston pin to deck height is aprx. 18mm
GR650 Piston Wrist Pin is 18mm

GS400 Piston Wrist pin is 16mm
GS500 cilinder on GS400X bottom end without gaskets is aprx. 16mm wrist pin to cil. deck height.

The GR650 piston at 0 deck depth will be good for a CR of 8.4:1 with stock dome, so I will need custom pistons (Wiseco)
The new conrods need to be 1 to 1.5mm shorter, to get to 0 piston deck to cil. deck clearance I will need to play around with different gaskets.

Why? You're cylinder can chain tunnel area doesn't match up to your block can chain tunnel area, so how did you propose to fix that? Figure your exact rod length difference, & do as Mekanix did & make a custom aluminum base gasket spacer. Heck, cosmetic or gasketstogo.com can make that for you if you give them specs or a cad drawing, or both engine's gaskets and careful notes or a sketch of the changes.

Then you'll have no messing with rods, and only have to worry about custom CP Carrillo/ Wiseco/JE Pistons.

What will be the major complaint of having 16mm wrist pins on that large of a piston? Curious, as I am running 72mm MTC's now on a gs750 with 16mm pins, & was considering a gs450 sleeved GS425 engine with 73mm (502cc) or 74mm (516cc) CP Carrillo pistons & head/block work from Rapid Ray for my next winter's project.

[GregT]

What will be the major complaint of having 16mm wrist pins on that large of a piston? Curious, as I am running 72mm MTC's now on a gs750 with 16mm pins, & was considering a gs450 sleeved GS425 engine with 73mm (502cc) or 74mm (516cc) CP Carrillo pistons & head/block work from Rapid Ray for my next winter's project.

Stiffness of a tube (which a gudgeon pin is) goes up as the square of the diameter. 2mm increase in pin OD represents a very large increase in stiffness. Some can be gained by increased wall thickness but this brings more weight with it.
Personally, I wouldn't go bigger than your current 72mm on a 16mm pin. 2mm bore increase represents a substantial loading increase on the pin.

Remember that the early motors had 16mm pins but as soon as the revisions and redesigns came with later motors and capacity increases, Suzuki went to 18mm pins. Later still, pins got bigger again.

[Chuck78]

Hmmm... Bumping a gs425 up to 502cc's seems to be quite a lofty accomplishment in displacement, so I think I will still shoot for that. A friend on here had some 11:1 71mm JE Pistons made, so without any custom molds & calculations, I could get another set of those made, and that would be a 4mm overbore on the gs425 sleeves same as a wiseco 844 kit in a gs750, so as long as the 425 isn't using the same sleeves as the 400&750, that may bore right in. I'd rather have thicker sleeve walls however, so using some 450 sleeves with a 71mm 475cc / 72mm 489cc / 73mm 502cc setup seems to be the way to go. I'm really shooting for the 500+cc mark. Afraid to go much bigger for heat issues with less metal around the cylinders as well as bore rigidity & potential distortion.

I think with a megacycle street performance can & springs, bigger valves by RapidRay, & 489/502cc, a seriously lightened GS twin of this nature (330lbs with screaming performance engine & very dialed performance suspension&brakes) would be an absolute blast to rocket through the tighter twisties with, & may have enough power to even take on a 4-6 hr ride to the Appalachian/Allegheny Mountains with camping gear to pursue the tightest West Virginia roads...


For Ren's bike, maybe custom rods are necessary to get the larger pin & GR650 sized pistons? I would honestly try to maybe downsize to 75mm or 76mm on the pistons compared to the GR (are those 76 or 77mm???) if the pin strength is an issue. Maybe a thicker pin & lighter CP Piston would do it?

[Rensdw]

I still think this thread should be move to Performance/Tuning/Mods, can any of the moderators help me out?

GregT;
I want the extra flow and pressure because I am most likely going to run a oil cooler with a thermostat and an adjustable oil relief valve, so a little bit of extra overcapacity would't hurt.
I'm going to do this because of the extra heat the engine will be producing and I'm just not gonna guess, I'm going to monitor the pressure and temperature to make sure the engine is running properly.
But you are right, if its too big of a hassle to change the ratio of the pump then I'll leave it, when the pressure turns out to be too low I don't have to take the whole engine apart, no big deal.

Chuck78;
Why? because I think it's fun.

The tunnel doesn't match up perfectly but luckily the chain is flexible, and I will most likely end up modifying or making custom chain guides.

Major complaint of the smaller 16mm gudgeon pin is strength/stiffness (like GregT said) and reliability.
I don't have the engineering skills to say/guess that "it will be fine" and I need different conrods anyway, since these are too long.

The aluminium spacer is something I thought about but having to move the studs at the same time made it too complicated/weak

Why would you think I should downsize? remember that is is a very heavy duty crankshaft with big (BIG!) roller bearings that were also uses on the GS1150 (should check that, could have been the 1100).
The only weak spot is the 16mm gudgeon pins, get rid of those and you have a crankshaft that should be able to take a lot of punishment.


Started polishing the combustion chambers, just to make it look nice



A collegue of mine gave me this spring tensiometer to match up the valve springs, it will help the engine to run smoother.
All the springs had a maximum of 1.5 pounds difference compared to each other, the exhaust springs being the lowest, not bad.

[GregT]

When/if you do modify the oil pump, I wouldn't change the relief valve setting. It will be pretty low because with a roller bearing crank you're not pushing the oil against any real resistance. By all means increase the VOLUME going to the head as this is where you'll get most gains.
Everything now hinges on what you find when you split the crank. If the big end pins are usable great. If not you'll have to look for a good crank.
When i did the two CB450 race cranks I have here, we split 5 cranks to find two good ones. Then none of the rods were usable as all had worn big end eyes from the roller cages rubbing. So it was custom rods using Suzuki DR200 big end bearings which were the right ID for the pins and the right width. 3.5mm rollers Vs the oddball Honda 3.7mm mega expensive replacements.
I'd be interested in the pin diameter and the width of the big end eye as it may be possible to source something better which will fit.

[Rensdw]

When/if you do modify the oil pump, I wouldn't change the relief valve setting. It will be pretty low because with a roller bearing crank you're not pushing the oil against any real resistance. By all means increase the VOLUME going to the head as this is where you'll get most gains.
Everything now hinges on what you find when you split the crank. If the big end pins are usable great. If not you'll have to look for a good crank.
When i did the two CB450 race cranks I have here, we split 5 cranks to find two good ones. Then none of the rods were usable as all had worn big end eyes from the roller cages rubbing. So it was custom rods using Suzuki DR200 big end bearings which were the right ID for the pins and the right width. 3.5mm rollers Vs the oddball Honda 3.7mm mega expensive replacements.
I'd be interested in the pin diameter and the width of the big end eye as it may be possible to source something better which will fit.

I am still designing the oil system in my head, biggest issue is separating the roller bearing lubrication from the camshaft plain bearing lubrication, I might be working with jets to keep the low end pressure low and head pressure higher.

I don't think the Suzuki crank has the same problem you are describing, but it sure is an interesting piece of information, I'll make sure to get back to this.
Still I haven't decided whether I wanna keep the balancer shaft or not, I want this bike to be reliable and I just don't have the experience to make a good decision.
Wiseco never replied to my quote request, and I am out of town for over a week to do a job, I will call them afterwards.

[Rensdw]

Custom high compression GR650 pistons

I just called wiseco, they are asking a very good price per piston, a complet kit is going to cost aprx. 300-350.
They have to make a minimum of 12 pistons, so....... Who is interested?

the pistons will be made to gr650 specs except the dome, compression will be raised to 10.5:1 static.
Not sure about gr650 stock camshaft valve clearance, im going to use custom camshaft so i dont worry about it.

[Chuck78]

Hmmm... To get 6 GS/GR owners interested in this, I would think it'd be a lot more appealing if you had them made in a +.5mm oversize (or +1.0mm o.s.) for current GR owners to have more of a reason to purchase/upgrade to these. 5 more people to buy. The GR is rare, so you'll have to post a specific thread on here. Dotheton.com, maybe caferacer.net in order to get more people interested.

JE Pistons will make one-off runs if you cannot find 5 more people. Carrillo "CP" makes the absolute best, lightest, & most advanced pistons, so for the weight factor alone, I would be contacting them if I were you. In your case, you are going with a much larger bore than stock, so with a bigger piston, its very critical to keep the piston weight within 10% of the original piston intended for that crankshaft. The CP will be the lightest (& best in every category by far, other than price).

[Rensdw]

Hmmm... To get 6 GS/GR owners interested in this, I would think it'd be a lot more appealing if you had them made in a +.5mm oversize (or +1.0mm o.s.) for current GR owners to have more of a reason to purchase/upgrade to these. 5 more people to buy. The GR is rare, so you'll have to post a specific thread on here. Dotheton.com, maybe caferacer.net in order to get more people interested.

JE Pistons will make one-off runs if you cannot find 5 more people. Carrillo "CP" makes the absolute best, lightest, & most advanced pistons, so for the weight factor alone, I would be contacting them if I were you. In your case, you are going with a much larger bore than stock, so with a bigger piston, its very critical to keep the piston weight within 10% of the original piston intended for that crankshaft. The CP will be the lightest (& best in every category by far, other than price).

Thank you for this information, very helpful, I will certainly be contacting those companies tomorrow.
I was thinking about keeping 3 sets for myself, for future projects, that leaves 3 kits to sell.

[Rensdw]

I have contacted cp carrillo and they are going to make me a single set of pistons, maby even the rod I forgot to ask.
Anybody interested in buying my gr650 cilinders? Its on ebay.

[Rensdw]

First: I would still like to have this topic moved to "Performance/Tuning/Mods" if one of the moderators reads this, please move this topic.


So, not a whole lot has happened, CP Carillo is done making my pistons but the rods are still in the making, that is going to take another month or so.

I did paint my engine, here some pictures:

First a nice high quality basecoat.




And 5 layers black paint and three layers clear coat later:
(All the white dots are reflections, there is a lot of lights in the hangar )





Little bit of dust in the paint here ;/ not bad for a outside paintjob though.








Also most of the aluminium is polished, like a mirror!





Next I will have to make the cilinder and head look pretty, I need to finish the external oil lines and then build up the bottom end.
All the chain guides seem to line up nicely, more on this later.