Re: Hobbit DR Temperatures?

Beard Road Bruiser (SoB) /

How did you plug the decomp? After pulling the plug out of the combustion chamber (effectively lowering the compression) I am wondering about just how low Hobbits can go on compression without suffering badly. If you tapped the channel and put a bolt in there, I wonder how twisting it out (lowering compression) would affect the engine.

Re: Hobbit DR Temperatures?

[Radium City] kyle k $ /

I went ahead and bought the "big fatty" head from 77 the other day but stock bolts are too short to put it on...bummer. new m7 studs in the mail. I will follow up with temps I get. this head looks massive compared to the stock one though and I can't imagine it not helping cool a significant amount.

Re: Hobbit DR Temperatures?

Hopefully you have success with your m7 stud conversion. Your almost ready for a Athena kit at that point ;P

Re: Hobbit DR Temperatures?

[Radium City] kyle k $ /

yea that head is machined for the Athena but whatev, I can't see

it being a problem. the stud conversion seems easy, just like threading any other hole but I can see my petcock will most likely be in the way and be another one of those things that makes hobbits so "charming"

Re: Hobbit DR Temperatures?

[Radium City] kyle k $ /

So i've been rolling with the big fatty head for a few days now. I've atached a few pics to show a comparison. It is much beefier than stock I would say. Went for a ride today to see my temps.

I firstly did some cruising speed through town at about 25-35. It was pretty neat because if i kept on the same throttle position as it gained speed to about 30ish the temp would get up to 370's then drop about 5-8 degrees. Was feeling good about it, i mean thats how air cooling works but never did before.

Then we get to the high speed temps. The road i do this on is a slight hill so back and forth is downhill/uphill. the first slight downhill half mile i maxed at 408, looking alright. Stopped an cooled to 375 and did the slight uphill. This time i hit 430. second time i maxed 415 and 433.

Overall I would say that this head upgrade is not the answer for staying below 400 on wot. It's just not gonna happen that easily. There was a noticeable increase in time that it took to get to these temperatures and when you lay off to cool it down temps drop to 380's very fast compared to stock. all of this said tho, it is a high comp head and staying at same temps as without high comp. I'm happy with it so far.

photo1.JPG
photo2.JPG
photo.JPG

Re: Hobbit DR Temperatures?

lower your compression

Re: Hobbit DR Temperatures?

Hmm, so I was under the impression that head had clearance issues with the tank. Looks like yours is good to go. No decomp? Probably does not matter. I was running the Motzing high comp and never used the valve anyway. It looks like you skipped the head gasket, no issues there? And also, how did you like it performance wise? Better low end? Loose any speed up top?

Re: Hobbit DR Temperatures?

[Radium City] kyle k $ /

I haven't had a chance to really test it out a whole lot yet, working 2 jobs will cut into ur riding time. it does give it a little more kick on the low end, not a bunch but throttle response seems improved from stops. i havent maxed out speed yet because I want to check for leaks after getting to temp a few times then retorque. the studs are new also because stock is too short so im taking it slow to see if they want to wiggle loose for any reason. petcocks with the bowls on the bottom will be a problem tho, gets all up in ur way. oh and I did end up using a head gasket afterwards.

Re: Hobbit DR Temperatures?

Welp, I'm at about the 30 mile mark of breaking in my de-glazed/honed DR cylinder post seize. Kind of crazy cruising around at 430 and hitting 450 like its nothing. BTW, that new fiber reinforced silicone rubber hose for mounting carburetors (via treatland) is so awesome. My air leak is gone for now. So, I hear people say temps go down when the cylinder breaks in, but how much? Like 10 degrees or something?

2nd question: Do small carburetors cause higher temps? I was thinking about this and it started to make sense to me. Less flow, perhaps less cooling? Has anyone changed the stock carb out for a larger one and noticed a drop in temps?

Re: Hobbit DR Temperatures?

OG Crazy Wayne /

On Hobbits with cast iron cylinders you can go about 445 degrees before you need to panic if you have your choke setup to work off the decomp lever you can just flick the choke on for half a second to knock your temperatures down.

Now on the Athena kit I've tried to blow one up and hit 487 degrees and it didn't cease but I flick the choke to cool it back down.

On cast or aluminum I try to Target in my temperatures to 420 degrees running wide open throttle.

On air-cooled systems Peak power happens at 418° reading from a thermal coupler at the base of the spark plug.

But your fuel mixture and timing must be correct.

And don't run a hot spark plug like a six or seven in the heat range the little arm and or tip of the porcelain on it will get cherry red and give you death rattle destroying everything.

I run bu8h and b8hs in most of my setups.

Re: Hobbit DR Temperatures?

> OG Crazy Wrote:

> -------------------------------------------------------

> On Hobbits with cast iron cylinders you can go about 445 degrees before

> you need to panic if you have your choke setup to work off the decomp

> lever you can just flick the choke on for half a second to knock your

> temperatures down.

>

> Now on the Athena kit I've tried to blow one up and hit 487 degrees and

> it didn't cease but I flick the choke to cool it back down.

>

> On cast or aluminum I try to Target in my temperatures to 420 degrees

> running wide open throttle.

>

> On air-cooled systems Peak power happens at 418° reading from a thermal

> coupler at the base of the spark plug.

>

> But your fuel mixture and timing must be correct.

>

> And don't run a hot spark plug like a six or seven in the heat range the

> little arm and or tip of the porcelain on it will get cherry red and

> give you death rattle destroying everything.

>

> I run bu8h and b8hs in most of my setups.

Amen to that I run a 8 on my fast maxi I dropped 40f switching from a thin wire iridium 6

Re: Hobbit DR Temperatures?

> Adam Smith Wrote:

> -------------------------------------------------------

> Amen to that I run a 8 on my fast maxi I dropped 40f switching from a

> thin wire iridium 6

Why this is tagged on a 7 year old thread , IDK .

Anyway , are you still running iridium , only an 8 instead of a 6 ?

Re: Hobbit DR Temperatures?

> P D Wrote:

> -------------------------------------------------------

> > Adam Smith Wrote:

>

> > -------------------------------------------------------

>

> > Amen to that I run a 8 on my fast maxi I dropped 40f switching from a

>

> > thin wire iridium 6

>

> Why this is tagged on a 7 year old thread , IDK .

>

> Anyway , are you still running iridium , only an 8 instead of a 6 ?

Nope sacked that off just a regular Ngk.

Re: Hobbit DR Temperatures?

Ungapped rings to bind them all /

Was goofing around with the heat issue on the DR with 12mm carb and added some copper surface area..

A94BF47F-A526-4AE3-BD44-9683564FBBD0.jpeg

. Doesn’t dampen the heating curve as much as hoped at WOT, but eliminates heat soaking and recovers freaky freaky fast. Does 45 flat and 53 downhill. Points & DOS variator with PAII rumpus.

Re: Hobbit DR Temperatures?

Does it play church music at idle? :)

Re: Hobbit DR Temperatures?

Brandon Weiss (Detective brandon to you) /

Looks like an Apache helicopter with all those cannons

Re: Hobbit DR Temperatures?

Ungapped rings to bind them all /

Cold probably tune it to play something ! - good winter project ;)

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account