Cylinder Head Temperature Differences

Are ya having a problem with your rig? We'll try to help. Share your tech tips and experiences here. Dr. Billy Glaser, author of the "Unofficial 750 Ural Service Manual" site myural.com, is moderating this section.
Forum rules
Here is the place for you to ask questions about or share your experiences about servicing or repairing your Ural or Dnepr. Please post topics concering modifications or accesories in the "Modifications and Acessories" section. Please post oil related questions in the "Oil Threads" section.
Post Reply
brookscooper
Party Member
Party Member
Posts: 149
Joined: Tue Oct 19, 2010 6:41 pm

Cylinder Head Temperature Differences

Post by brookscooper » Tue Jul 02, 2019 1:47 pm

So, after my adventure a few years ago where I soft seized the left piston in the jug, I decided to add a dual CHT gauge to the bike so I'd have warning if I was overheating so I could stop and cool before doing damage.

First ride of any length was today. The left head consistently reads 20 - 25C cooler than the right.

If this were your rig, would that concern you? What, if anything would it prompt you to do?

Carbs are balanced, valves set correctly, carbs have same jets, same needle positions, etc. Timing is correct. Engine runs great, smooth (for a Ural) and strong. So, no subjective signs of problems.
2004 Black / Chrome Tourist
Portland, OR

Donbmw
Hero of the Soviet Union - 2019
Hero of the Soviet Union - 2019
Posts: 313
Joined: Fri Nov 18, 2016 7:47 pm
Location: Monroe, Louisiana, 71203

Re: Cylinder Head Temperature Differences

Post by Donbmw » Tue Jul 02, 2019 2:06 pm

On my rig the RH is about that much cooler thane the LH. From other post here the RH is normally the cooler side.
2015 Patrol, 1980 R65, 1982 R65 bought new, 1975 R 90/6, 1959TR3 Triumph

Don

User avatar
Wanderrad
Hero of the Soviet Union - 2019
Hero of the Soviet Union - 2019
Posts: 679
Joined: Wed Jan 28, 2015 2:54 pm
Location: NY North Country

Re: Cylinder Head Temperature Differences

Post by Wanderrad » Tue Jul 02, 2019 2:25 pm

Completely normal.

Edit: sorry, I didn’t do the math right. 20-25 C does seem like a bit much. Mine runs about 10C difference at 60 MPH and they quickly balance when I come to a stop.
Last edited by Wanderrad on Wed Jul 03, 2019 6:29 am, edited 1 time in total.
-Scot

Current rides:
2018 Gear Up, Olive Drab Matte "Bad Penny"
2018 H-D Road King Special, Industrial Gray Denim

User avatar
Peter Pan
Order of Suvarov
Order of Suvarov
Posts: 3422
Joined: Fri Jan 31, 2014 11:30 pm
Location: Heredia, Costa Rica/screwing the heck out of the hack

Re: Cylinder Head Temperature Differences

Post by Peter Pan » Tue Jul 02, 2019 3:42 pm

Double check wih Infrared thermal gun, might be the sensors are crossed over. My Sophie too used to have the left side always hotter, before I took off the vacuum hose from the gasoline valve. Once with manual gas cock both cylinder heads use to stay within 5ºC (correctly called 5K as Kelvin). Typically 115-185ºC depending on weather and climbs.
Sophie Travelair = Patrol 2013
8 weeks 12.000km Oregon-Alaska-Oregon
With a DIY foam air filter the rig runs well even in tropical rain = :moto:
Final drives: 1. at 5000km, 2. at 34.000km(+friction plates) 3. at 42.386km
transmission: 1. 40.000km. 2. installed
Engine: 1. 43.388km crank replacement: Back on the road since 23.Okt.2019 :party:

The Avatar are 2 rice grains stating life's essence:
"The most important you cannot see!"
=> Attitude makes the difference!

User avatar
chaos2
Order of Victory
Order of Victory
Posts: 5001
Joined: Sun Apr 29, 2012 12:58 am
Location: sw ohio

Re: Cylinder Head Temperature Differences

Post by chaos2 » Tue Jul 02, 2019 9:31 pm

the chair side usually runs cooler because of the air funneling by the head. Mine RH cylinder usually runs about 20F cooler, 20C seems a bit much.
past afflictions include limey motocars and bikes, R60/2, R65ls, and a Citroen.
Now an 87 K75s, DB Haanjo gravel bike, and a rusty 2012 GU bought new
dual K&N cones on homemade intake, 40/137.5
Raceway needles, Modtop exhaust
$29 VW Hydraulic steering dampener

brookscooper
Party Member
Party Member
Posts: 149
Joined: Tue Oct 19, 2010 6:41 pm

Re: Cylinder Head Temperature Differences

Post by brookscooper » Wed Jul 03, 2019 10:26 am

So, this engine takes a looooonng time to fully come up to temp. The ride home yesterday had a lot more uphill travel and thus, more heat generated. By the end of the ride the two sides were nearly Identical. As a toy, the CHT is fun, for longer rides or ones really involving bills it will be very useful.

Both sides stabilized at right around 175C and varied only slightly with changes in load. I’ll always wonder how hot the rig was when I killed the left piston and jug. Ah well, she’s back on the road and running well.
2004 Black / Chrome Tourist
Portland, OR

Post Reply