View Full Version : Hatori pipe

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04-10-2005, 04:17 AM
Hi guys finally flying my spectra, and i love it. Using a standard 231 it was smooth from the start.I have put 7 or 8 tanks through so far, went to put another through and found that the pipe had come loose. Now you might say whats he complaining about, but the motor was as smooth as you could expect, no vibration in the tail fins etc. and yet it still comes loose. A mate of mine has a spectra as well, with a TRM 231 in and the same pipe. His has nearly 3 gallons through but has had numerous similar problems with the pipe coming loose. I can't believe most people using this pipe are not having the same frustrating problems. There are hundreds of gassers and glow helis out there that don't require refitting the pipe every few tanks of fuel. Are there better pipes, perhaps one with a smaller header, not a heatsink like the hatori. I saw a post showing the zimmerman 2019 with a small header pipe, can anyone comment on these pleeeeeeaaaaasse!!! :arggg:

04-10-2005, 07:39 AM
I have some of the same things happening unfortunately. The adapter loosens from the motor but the pipe never does. The first fix I did was to put set screws into the adapter that "pinched" against the 2 bolts holding it to the motor. This helps a bunch but the adapter still works it's way loose.

Here are the reasons that I have found:

-The thermal expansion of the adapter (being aluminum) is fairly high. This adapter sees a lot of heat so it will expand when hot and contract as it cools. This heat/cool (expand/contract) cycling works the bolts loose.

-The Hatori is fairly long. This gives the pipe(muffler) a leverage arm to work up and down against the mounting as the adapter heat cycles. This works the adapter around and aids in the bolts loosening up.

-The two above (heat expansion/leverage) work on the adapter in the long run to elongate the holes through the adapter making more room for the leverage to work against the bolts. This means that the holes through the adapter are getting loose and sloppy.

My Hatori has stayed on the model now for over 25 flights. I thought that it had loosened at the field yesterday, but it had not.

Things you can do to keep your existing Hatori on:

-Use red lock-tite and the use of lock washers on the adapter bolts. Red RTV can also be used.

-Use "crushed nut" type aircraft locking nuts on the back side of the bolts holding the adapter on. You will have to use longer mounting bolts and possibly remove a small amount of cooling fin from the back side of the motor flange area, but it can be done. Caution!! If you use this method, a crash could result in breaking the cylinder on your motor!!

-Install the adapter using lock washers and red lock-tite. Leave the muffler/pipe off and the start the motor and let it idle for a couple of minutes to heat up the adapter. Tighten down carefully the bolts holding on the adapter and then tighten the set screws against the bolts. Be very cautious tightening the bolts after heating as you can get them too tight and strip the threads out of the cylinder!!
Then install the muffler/pipe as normal.

I am (as soon as I get the time to finish) having an adapter machined out of stainless steel which has much less thermal expansion than the aluminum. This should help with two of the three above listed items and possibly all three.

Hope this helps!!

04-11-2005, 01:41 AM
Thanks for your reply John, we thought the header expansion and contraction was the main problem.I think the stainless header might be a good idea, if you could eliminate the ex/cont. the bolts may handle minimal movement and remain tight :dontknow
But apart from that how do other pipes work on the spectra?eg bergen pipes, century torpedo, zimmerman 2819 , comments appreciated, cheers Kev

04-11-2005, 10:20 AM

Before using the Zimmerman I tried the Torpedo. Got the same things that had happened with your Hatori. After the third fly I have lost one of the 4th small screw and had to tighten all others. After the first fly, some aluminium finisher went off (as you can see at the picture) PS: this is written at the notice when you receive the muffler.
The muffler had not a nice look at all.
Then I bought the Zimmerman and fly with it for approx 1 gallon (never had problem with it). I tryed again the torpedo and have notice that the motor lost power. Also the Torpedo compare to the Zimmerman is 3 to 4db more loud.
If I can give you a tip, forget the Torpedo except if you have 100$ to lost.


04-11-2005, 05:50 PM
I didn't see in any of the posts about the Hatori wether or not you guys are using the stock zenoah exhaust gasket with the header adapter? I am contemplating installing it, any help would be great.

04-11-2005, 07:55 PM
I have used the gasket and also installed the pipe without it. It did not seem to make any difference (except for the gasket getting brittle after a while and crushing). I made up some gaskets for both the motor to adapter joint and the adapter to pipe joint out of some Grafoil material (graphite foil). This sealed the joints up very well and has no thermal expansion. The problem is, this stuff is super dainty, the least bit of mishandling and it falls apart.
Don't ask, I got the stuff from work :oops: :wink:


04-11-2005, 08:23 PM
Dave i had also used the zenoah gasket, and as i said before things were perfect then when attempting to start it the last time i noticed leakage between the header and the pipe.i thought the header was still tight to the motor but on further examination all the bolts had loosen up. i used high temp silicon to seal everything, as do most of the guys i fly with. We have no problems with the glow helis. the problem with these zenoahs is they generate and transfer so much heat, i don't know what the answer is??? :dontknow

04-11-2005, 09:56 PM
Thanks for the help! I have been thinking this over for a while. If you look at the zimmerman header pipe it uses a thin stainless flange at the cylinder joint, Not much material for expansion and the bolt grip length is kept to a minimum. My idea is to build the adapter out of a short piece of stainless pipe with stainless flanges welded on each end to attach the muffler and to the cyclinder. I may also use a press to square up the pipe to fit the shape of the port. May work, may not, but iI think I will give it a try. Let me know what you think.


04-13-2005, 07:30 AM
I will be talking to a machinest friend of mine today about making stainless header blocks for the Hatori. I will let you guys know what he says.

04-13-2005, 12:06 PM
I don't think that the expansion of the header block is the problem here...I'm a machinist and I looked up how much aluminum expands, I would be very surprised if we have more than .0005" to .001" expansion between the bolts and the exhaust port on the motor. For those who want to know, aluminum's linear expansion is it's .00001244" per degree F based on 1 cubic inch...! I think the real problem here is theres to much pipe hanging back of the two mounting bolts. Now the bolts will also do there own expanding and contraction but I don't think there the problem either or all pipes would be coming loose. Hears another thought if the bolts were at fault and expanding in length that would mean that the aluminum is not expanding and contracting enough to keep things tight...

I'm thinking of making a whole new #125-40 aluminum ladder and incorporating a muffler support into it... Another thought was to make two mounting brackets and mount the muffler straight onto the base plate of the heli and use a SS tube header with a Teflon damper so as the muffler is isolated from the motor.

For the price of this pipe...I won't go there!

Any thoughts...?

Cheers all

04-13-2005, 12:18 PM
Your right when saying 'For the price of this pipe.."
I am not using a Hatori pipe (Whith the Zimmermann never had problem!)
Maybe all of you should contact Hatori to fix the problem or ask MA to see with Hatori to fix it (as they said they have working with Hatori when building the Spectra). It seems that all Hatori owner have the same problem. My point of view is that in this case it is not to you to find a way to resolve the problem but Hatori has to do it.


04-13-2005, 05:07 PM
I agree the fix for this pipe does not lie with the purchaser, these problems must! have manifest during development of this pipe. Hatori has continued to sell this pipe and MA has continued to promote this pipe for the spectra and the TRM engine. I don't know about anyone else,but i'm not happy about refitting the pipe every few tanks for the rest of the spectras flying life. I brought a gasser for longevity, reliability and economy, looks like i will have to paid out more just to get it to fly long enough to run it in. Is Hatori and/or MA going to comment on this? :arggg:

04-13-2005, 05:45 PM
I'm getting 2 custom Stainless headers made for me and John to test. We will let you know what we find out ASAP. I have an engineer friend with a machine shop I am trading some computer work. ;) You gotta love a good trade.

I really like the Hatori and I will gladly change out the header if it cures the come loose problem. Quiet and powerful. Until tuned pipes come along, this Hatori is what I am going to run. John has tested a lot of mufflers.

04-14-2005, 08:48 PM
Then header is drawn on the cad machine. hopefuly will have some pics by Monday or Tues.

Stay tuned. :) Hope this helps make the Hatori stay put.

big dee
04-19-2005, 09:42 AM
its Wed any good news this a becoming a bit of a joke and iam not :lol: ive had a couple of fixes sugested to me one was "a 91 and mussle pipe "its :twisted: the other was :bomb: getting a bit :oops: and depressed and dont know what to do :arggg: someone come up withan :idea:

carey shurley
04-19-2005, 10:03 AM
one possible answer that I have not been able to test yet, is to make a copper gasket to fit between the cylinder and the header. It probably needs to be at least 1/16th of an inch maybe thicker. K&S sells copper sheets at most LHS but I haven't been able to get one cut to size yet. Might need to double up a couple of gaskets to get enough temperature differential

This breaks the aluminum/aluminum temperature connection which I think is really the problem.

You'll note that the exhaust gaskets on automobiles are made of a different metal than the head and header for this reason.

If somebody has time to cut one of these out and test it, post your results.

04-19-2005, 11:19 AM
I should have the SS headers sometime this week. We will let you know ASAP how they work.

04-23-2005, 06:42 AM
OK Guys,

The Headers should be finished very soon!! Here are some pics. Still a lot more cutting to go on them, but you can get the idea.

We will be testing these very soon, and hopefully they will work as planned. We will let you know. I have sent a PM or two to a couple of people about helping us test.

The photos below only show about 1/2 of the work making the headers. They will be cut down to make them light weight. Lets hope they fix the problem after all the work involved.

Hotshot Charlie
04-23-2005, 08:07 AM
It seems all the best machinists are named Fritz or Rolf. German/Austrian engineering, hard to beat.

04-23-2005, 08:26 AM
Looks great Will. The form of the shown adapter will be more easily drilled for my Hatori prototype than if it were in the same form as the Hatori adapter. The spread on the bolts (center to center) is a bit different on my pipe than the production model of the pipe. Looking forward to trying it out. This should make a big difference!

Later and Thanks!

04-27-2005, 04:55 AM
The headers look good Will, can't wait to see how they go.cheers Kev

05-06-2005, 07:26 AM
Still waiting on the headers......

Had to get a counterbore and it is not here yet. :DOH

05-06-2005, 09:25 PM
I was just browsing and saw this post.

John mentioned he was using "red" loctite. Is anyone using "high Temp" loctite (it is usually white in loctite brand or red in some other brands. I know the high temps stuff is really good with muscle pipes and such that tend to loosen easily. Here is a cut and past from their web site:

272 Threadlocker High Temp./High Strength

Withstands temperatures to 450F. Provides a fast cure on most surfaces including "as received" fasteners. Recommended for bolts up to 1 1/2" (36 mm) in diameter. Heat and hand tools are required for disassembly.

Just a thought. Some of you have probably already tried it.

05-09-2005, 03:09 AM
Interesting. My Hatori came loose in 2 flights this weekend. :( :arggg: Looking forward to trying the stainless headers very soon!! I will get some of this locktite to try. Thank you Eric.

05-09-2005, 12:57 PM
Not saying it will work :) but it is worth a try also.