Upper right cylinder seizure.....damn it!

General forum on engines, transmissions, gearing and modifications to each

Moderator: rztom

Message
Author
User avatar
2smoke
Posts: 662
Joined: Wed Apr 20, 2011 3:18 am
Location: Niagara, Ontario,Canada

Re: Upper right cylinder seizure.....damn it!

#16 Post by 2smoke » Sat Aug 22, 2015 10:19 am

The heads are known to warp. I have rebuilt 2 500 engines and the heads needed to be made true.
They will leak coolant as soon as you pour it in.
OEM head gaskets are a must.
People don't want to believe that they have to spend the money on OEM gaskets and seals.
Your seizure was right away. Something was not correct.
Let's see the piston.
The cranks are well made pieces and known to last a long time. You have to make the judgement call on whether they need a rebuild now or soon or later. If you can only feel a little side to side play when you rock the rod back and forth then it should be ok for a while but if there is obviously lots of play you are beat. Certainly easier to rebuild them now than to do another teardown later though.
Colin

maser01
Posts: 56
Joined: Tue Oct 02, 2012 8:16 am
Location: Australia

Re: Upper right cylinder seizure.....damn it!

#17 Post by maser01 » Sat Aug 22, 2015 11:03 pm

Thanks again for your honest comments, I guess I have my own "gut feeling" about the common seize issue (which will no doubt be debated which is a healthy forum) I'll get to that in due course as I build the engine.

As for the crank tolerances..........I can understand why people stick to the manual (better to be safe than sorry!) I cut my teeth on 2 stroke engines in 80's/90's both road and dirt and have rebuilt many crankshaft assy's and never had any fail under race conditions (touch wood) so I know about tolerances etc. I'll have a chat to some ex 2 smoke racer mates ie TZ/RS/RZ/YZ/RM who built there own engines for an opinion also.

I will double/triple check all the crank freeplay's in the correct manner ie V blocks and Dial gauge and rebuild as required. Don't get me wrong here...... I'm a "Do it once, do it properly" guy. If there's any doubt whatsoever Re-cranks they will be rebuilt to new STD.

I intend to split cases with the engine still in situ as these are designed for that capability so I'll let you all know how it all goes :-)
Love classic 2 Strokes
Regards,
T Newts

1984 Yamaha RZ500 L
1981 Husky WR430
1974 Yamaha DT175 B
1995 Suzuki RGV250 T
1979 Suzuki GS850 GN
2000 Husaberg FE600E
2004 Aprilia RSV1000r
1981 Yamaha IT250H

maser01
Posts: 56
Joined: Tue Oct 02, 2012 8:16 am
Location: Australia

Re: Upper right cylinder seizure.....damn it!

#18 Post by maser01 » Mon Aug 24, 2015 2:59 am

Will post some piston pics soon to get some views. On another topic.......anyone used the Yambits supplied con rod kits? They appear good value if my cranks need doing. :razz:
Love classic 2 Strokes
Regards,
T Newts

1984 Yamaha RZ500 L
1981 Husky WR430
1974 Yamaha DT175 B
1995 Suzuki RGV250 T
1979 Suzuki GS850 GN
2000 Husaberg FE600E
2004 Aprilia RSV1000r
1981 Yamaha IT250H

User avatar
pstamper
- - - - -
- - - - -
Posts: 1743
Joined: Fri May 09, 2008 8:56 pm
Location: Houston, Texas

Re: Upper right cylinder seizure.....damn it!

#19 Post by pstamper » Wed Jul 20, 2016 11:59 pm

I have no idea about engine parts, but value and quality? I would go with quality and what the engine builders on the forum recommend. I am sure that is a discussion that could get ugly. I consider myself blessed with my engines. As Rick said, I have more track miles on my RZ than most people ever put on their bikes. I am sure my engine will fail some day but plugs always look good, very little oil spatter on back of bike, and it pulls from 4k to 10 k with no hesitation. I run VP 98 race gas, change oil more than I should, run quality Klotz snowmobile injection oil, and Champion spark plugs. Only fouling is after transporting to a track that is more than 3 hours away and the float valves get stuck. Another track day the 30th on a shorter circuit so will be fun. Best of luck.

bogey
Posts: 150
Joined: Fri Dec 12, 2008 6:28 pm
Location: Skerries, Ireland

Re: Upper right cylinder seizure.....damn it!

#20 Post by bogey » Fri Jul 22, 2016 2:37 pm

Only have limited knowledge of the finer mechanical details of these bikes but in terms of running in 3 cycles of 60KM seems very low which is 180KM in total. My recollection of the advice given in relation to running in would have involved about 500 miles and as you clocked up the miles rev limit was to raised in fairly small increments and kept at each cap for period before raising again.

A couple of spins at low revs and then going straight to 8000 sounds a bit aggressive to me but maybe I am wrong. I have my bike almost rebuilt and ready to fire up so any advice on running in would be great!

User avatar
pstamper
- - - - -
- - - - -
Posts: 1743
Joined: Fri May 09, 2008 8:56 pm
Location: Houston, Texas

Re: Upper right cylinder seizure.....damn it!

#21 Post by pstamper » Fri Jul 22, 2016 9:57 pm

I am firm believer that heat cycles are way more important.

User avatar
Jeff B
Posts: 751
Joined: Fri Nov 18, 2005 6:15 pm
Location: Wisconsin

Re: Upper right cylinder seizure.....damn it!

#22 Post by Jeff B » Sun Aug 07, 2016 12:14 am

Check this out.
http://www.rzrd500.com/500phpBB3/viewto ... d&start=75" onclick="window.open(this.href);return false;

There is clearly better coolant flow around the lower cylinders than the upper cylinders. Typically not an issue with stock motors. This makes the uppers more susceptible to minor issues. Make sure that there is good coolant flow through the tiny hoses connected to the upper barrels.

maser01
Posts: 56
Joined: Tue Oct 02, 2012 8:16 am
Location: Australia

Re: Upper right cylinder seizure.....damn it!

#23 Post by maser01 » Wed Aug 10, 2016 8:33 am

Jeff B wrote:Check this out.
http://www.rzrd500.com/500phpBB3/viewto ... d&start=75" onclick="window.open(this.href);return false;

There is clearly better coolant flow around the lower cylinders than the upper cylinders. Typically not an issue with stock motors. This makes the uppers more susceptible to minor issues. Make sure that there is good coolant flow through the tiny hoses connected to the upper barrels.
Yes agreed as I suspected. Since re-fitting OEM std pistons, rings, pins and L/E bearings and light hone the bike has been run in and running sweet! Found std size "Mitaka" pistons too tight in std bores even after bike had travelled in excess of 40k Km........yep 40,0000km! Really surprised me, which means the "Mitaka" std size pistons were produced slightly bigger diameter than OEM..........hence the seizure :smt010 So lesson learn't.............never assume anything...........measure it!

I also decided to fit rear manifolds with the oil injector on the top to help rear cylinder lubrication and works well with nice even light smoke on all 4 pipes during warm up and clean burn plug colour (ie light brown/tan). I decided that the engine intake vacuum would allow the oil to be more easily "Ingested" as it fell into the manifold rather than being pumped into a pool that sits in the manifold. I ride the bike hard on occasions and it hasn't missed a beat so I'm comfortable with the above assumption rather than have the injector on the bottom as per std procedure!

Just ordered set of JL GP Stainless pipes to help get this super old giant killer breathe easier! Anyone have any suggestions for mods to get the most out of the pipes with stock carbs? :smt003

Cheers,
Love classic 2 Strokes
Regards,
T Newts

1984 Yamaha RZ500 L
1981 Husky WR430
1974 Yamaha DT175 B
1995 Suzuki RGV250 T
1979 Suzuki GS850 GN
2000 Husaberg FE600E
2004 Aprilia RSV1000r
1981 Yamaha IT250H

bogey
Posts: 150
Joined: Fri Dec 12, 2008 6:28 pm
Location: Skerries, Ireland

Re: Upper right cylinder seizure.....damn it!

#24 Post by bogey » Wed Aug 10, 2016 9:42 am

Hi,

So then, in relation to breaking in using heat cycle process what is the correct procedure for doing this??

Any help or comments appreciated as I hope to be at this stage shortly.

Regards
B

User avatar
Jeff B
Posts: 751
Joined: Fri Nov 18, 2005 6:15 pm
Location: Wisconsin

Re: Upper right cylinder seizure.....damn it!

#25 Post by Jeff B » Wed Aug 10, 2016 9:04 pm

maser01 wrote: Yes agreed as I suspected. Since re-fitting OEM std pistons, rings, pins and L/E bearings and light hone the bike has been run in and running sweet! Found std size "Mitaka" pistons too tight in std bores even after bike had travelled in excess of 40k Km........yep 40,0000km! Really surprised me, which means the "Mitaka" std size pistons were produced slightly bigger diameter than OEM..........hence the seizure :smt010 So lesson learn't.............never assume anything...........measure it!
Also there's the cast vs. forged piston differences. One needs more clearance than the other because they expand more with the heat. Not sure what Mitaka are.

maser01
Posts: 56
Joined: Tue Oct 02, 2012 8:16 am
Location: Australia

Re: Upper right cylinder seizure.....damn it!

#26 Post by maser01 » Thu Aug 11, 2016 8:14 am

bogey wrote:Hi,

So then, in relation to breaking in using heat cycle process what is the correct procedure for doing this??

Any help or comments appreciated as I hope to be at this stage shortly.

Regards
B
Well, provided you have correct piston to cylinder clearance and I'd be ensuring your cooling system and lubrication systems are operating perfectly BEFORE running the bike for any length of time. Bike run in is a personal opinion but I like to ride the bike keeping it under load through the gears without high revving varying the RPM without "Lugging" ie riding a gear too high etc. Certainly get the engine to operating temp before setting off on a ride and advisable to let "heat cycle" for approx. 30min cool down between rides to assist in ring "Bed in" process. I feel these are the most important basic things to successful running in....in my little opinion, others may differ slightly! Good luck but most of all have fun :smt006
Love classic 2 Strokes
Regards,
T Newts

1984 Yamaha RZ500 L
1981 Husky WR430
1974 Yamaha DT175 B
1995 Suzuki RGV250 T
1979 Suzuki GS850 GN
2000 Husaberg FE600E
2004 Aprilia RSV1000r
1981 Yamaha IT250H

Johnyh
Posts: 45
Joined: Wed Jul 09, 2008 6:22 am
Location: Gloucestershire, UK

Re: Upper right cylinder seizure.....damn it!

#27 Post by Johnyh » Wed Sep 14, 2016 4:34 pm

When I rebuilt mine I had major problems with rear cylinder seizures. It kept seizing on part throttle doing steady mph, on stripping down I always found the piston to be scuffed front and back but covered in oil!!!! The bores are not standard (I can't remember what size they are) and we found that the power valves were the cause of the problem, protruding into the cylinder. A couple of minutes with the dremmel and no more seizes.

silverstrom
- - - - -
- - - - -
Posts: 3236
Joined: Sat Feb 04, 2012 7:36 am

Re: Upper right cylinder seizure.....damn it!

#28 Post by silverstrom » Wed Sep 14, 2016 8:57 pm

Johnyh wrote:When I rebuilt mine I had major problems with rear cylinder seizures. It kept seizing on part throttle doing steady mph, on stripping down I always found the piston to be scuffed front and back but covered in oil!!!! The bores are not standard (I can't remember what size they are) and we found that the power valves were the cause of the problem, protruding into the cylinder. A couple of minutes with the dremmel and no more seizes.
Your bore size had to be approaching 58 mm for that to happen, or you had non-standard valves.

Post Reply