R1150RT and Autolite 3923 plugs

[Linz]

Hi all.

Taking the advice from this forum, I ordered a set of Autolite 3923 plugs for my '02 R1150RT. I then read on another forum that for 1150's, the correct plug is actually the 3922.

 

I'm wondering if anyone is successfully running 3923's in their 1150's or if I have to send 'em back and change them for the colder 3922's...

 

It seems to me that the slightly hotter 3923's would be better for my non-standard RT (Techlusion unit) as it's running richer than stock.

 

Anyone with any experience want to comment please?

 

Linz

[John in NC]

My 2004 RT loves the 3923. I bought a set of two platinum at Wal Mart for $4.27. 3923 is a very common plug in this country.

[Huzband]

Had 3923's in my '02 RT.

 

Ran fine.

[Jim Moore]

3923s in my 1150GS. 83K miles on it, so I'm reasonably confident in the plugs.

[Perlova]

Hi all.

Taking the advice from this forum, I ordered a set of Autolite 3923 plugs for my '02 R1150RT. I then read on another forum that for 1150's, the correct plug is actually the 3922.

I'm wondering if anyone is successfully running 3923's in their 1150's or if I have to send 'em back and change them for the colder 3922's...

 

It seems to me that the slightly hotter 3923's would be better for my non-standard RT (Techlusion unit) as it's running richer than stock.

 

Anyone with any experience want to comment please?

 

Linz

 

I had Autolite 3923 platinums in my 1100RT and replaced them with plain 3923's. The bike did not run as smooth, so I put the platinums back in.

[270]

My 2004 RT loves the 3923. I bought a set of two platinum at Wal Mart for $4.27. 3923 is a very common plug in this country.

 

You're running the 3923...what are you running for the secondary plugs? Just curious...

[Linz]

Thanks for the replies. The other forum indicated that a 3923 induced meltdown of all moving parts would be the result of my folly.

I'll gap 'em and bung them in then...

 

Linz

[cooke45]

I put 3923's in my 03'RT last summer and it runs very well- way better than with the BMW specified plug.

[RFW]

It seems to me that the slightly hotter 3923's would be better for my non-standard RT (Techlusion unit) as it's running richer than stock.

 

Anyone with any experience want to comment please?

I cannot see any reason why a slightly hotter plug would be of any benefit whatsoever unless you are running so grossly rich that there is a sooting problem. If this is the case, then you need to cure the disease, not the symptom.

 

Also cannot understand why you would want to use something other than the plugs BMW specifies. Are you just theorizing that you might have a problem? Is there really a problem that needs solving with a different type of plug? Is the motor actually missing? In the case of spark plugs they either fire the mixture or they don't.

[PapaJ]

I'm running the 3923's in my 02 1150RT because they help eliminate the surging, the stock plugs didn't.

[richrob]

on the platinum 3923 for a '03 1150 rt, I was told a gap of .040 would be correct. Is that the setting you are using? Thanks.

[Linz]

The plugs have been gapped and installed. The bike has been taken for a good hard test run and it went brilliantly. There's a little more to get from the throttle bodies on the next service but she's 95% there.

Very happy with this knowledge base, thanks to all.

 

Linz

[jfremder]

My 2004 RT loves the 3923. I bought a set of two platinum at Wal Mart for $4.27. 3923 is a very common plug in this country.

 

You're running the 3923...what are you running for the secondary plugs? Just curious...

 

Information I had gotten from a previous post on this topic:

 

Primary = Autolite 3923

Secondary = Autolite 4162

[270]

My 2004 RT loves the 3923. I bought a set of two platinum at Wal Mart for $4.27. 3923 is a very common plug in this country.

 

You're running the 3923...what are you running for the secondary plugs? Just curious...

 

Information I had gotten from a previous post on this topic:

 

Primary = Autolite 3923

Secondary = Autolite 4162

 

 

Thanks!

[richrob]

What did you gap the plugs??????

[Bob_Minor]

It seems to me that the slightly hotter 3923's would be better for my non-standard RT (Techlusion unit) as it's running richer than stock.

 

Anyone with any experience want to comment please?

I cannot see any reason why a slightly hotter plug would be of any benefit whatsoever unless you are running so grossly rich that there is a sooting problem. If this is the case, then you need to cure the disease, not the symptom.

 

Also cannot understand why you would want to use something other than the plugs BMW specifies. Are you just theorizing that you might have a problem? Is there really a problem that needs solving with a different type of plug? Is the motor actually missing? In the case of spark plugs they either fire the mixture or they don't.

 

People on this forum can be pretty much be divided into two groups. Those with a skepticism for the Autolite plugs and those who have used them. They just plain work, and if your bike surges, they make a very pronounced improvement. I think Bosch probably did a great sales job on the BMW engineers when they talked them into specifying the inferior multi-elctrode plugs.

[John in NC]

Just did the 30k service yesterday and replaced the platinum autolite with the double platinum autolite APP3923. Even better performance now. Still using the 4162 as secondary and they are always rather sooty and black when I remove them. Just like the BMW plugs. Has anyone used something other than 4162 that did not come out looking that way?

[JamesW]

I hate to dredge up this subject yet again but after yesterday I gotta do it. I was, I say was, one of these people that thought all this Autolite plug talk was just a lot of BS. That was until yesterday. I bought a pair of AP3923 plugs a month ago and decided to give 'em a try all the while thinking what a waste of time. Anyway, I gaped them at .040" and put them in. It was about 25 degrees in the garage but you would have thought it was a summer day when that 1150 fired up right now and then settled down to one of the smoothest idles I have ever heard on any motorcycle period! Went for a really short ride and no trace of a surge just smooth power output and I do not exagerate. End of story

[Silver Surfer/AKAButters]

I have been using 3923s (plain) for over 20K miles and the bike runs great. Less than $2 ea.

[Linz]

James, I'm glad it worked for you. This forum is full of wonderful advise and some of it may look a little too fanciful to take seriously until you try some of it.

 

The cost of a couple of plugs isn't going to break the bank or harm the bike so, why not try it?

 

Reason dictates that one spark plug is much like another. Spark, compression, fuel = bang. The reality for some is different...

 

I'm onto my second OilHead after a happy experience with a '94 R1100RT, sold in June '06 after 100,000Km of reliability save for gearbox issues around 60,000Km.

 

After almost a year of missing my Beemer I bought a very low Kilometer (13,000) 2002 R1150RT. This bike has been a pig as far as surging is concerned. There are those on this forum who claim that surging just can't be that bad, and that, if you ride with loose arms (I do anyway), you wouldn't feel it.

 

I have news for those people...

 

So I listened to the Techlusion believers here and adding one improved the bike maybe 50-60%. The valve matching and throttle body matching believers then added their thoughts and I did my own service with all the correct gear as gleaned from Jim von Baden and the Dummies crew. Wurth feeler gauges were purchased, TwinMax and thin walled 10mm Hazet spanner (expensive) all bought according to the rules and the information applied correctly.

 

Bike now at around 90%, just a touch of surging left. Liveable, acceptable but not totally cured. I will say that power output, willingness to get up and go all were greatly imnproved over my bike's stock condition. It was asthmatic, surging and generally a miserable example of the breed whose natural inclination was to be stopped in a garage somewhere other than doing what it was bred for...

 

The Autolite thread came along and I just had to try for the last 10%. Can't find those in Australia, not easily anyway.

 

The Autolite posters were very specific about plug gapping so I sprung for the little Snapon Tools adjuster to ensure I got that right and added the plugs to the bike.

 

I reckon that she's at 98% and seems to have a lot more power. She is very strong now and I feel the plugs have made a noticeable difference.

 

My personal conclusion is that a lot of little things worked with my particular bike to get it to where it should have been from the beginning. The biggest effect in my opinion was doing the valve job really well. It's where I felt the biggest gain was made, even over the Teclusion unit. This improved the way the whole bike ran, not just eased the surging.

 

You could argue that this bike has turned me into a mechanic of sorts, someone who has to tweak the bike to get it to run correctly and that would be true to an extent. It's also made me willing to listen to advise, however improbable such as in this thread, and find an improvement which could be measured by just riding the bike. Scientific?, No, but true nevertheless.

 

The dummies guide to valve adjsutment mentions, right at the end, that you'll become more senstive to how your bike is performing once you've experienced it running correctly. I've found that's true. They also say that the first adjustment will not last long but that with experience, you'll get it right faster and eventually, the bike will find its sweet spot and just stay there. I hope that's true.

 

Cheers and thanks for all the advise.

 

Linz

[JamesW]

Linz, I couldn't agree with you more. I too went the Techlusion route after carefully adjusting TBs and valves but there was still that 10% left. So, with much doubt and disbelief, I sprung for the Autolites and I just can't believe it! My 1150 absolutely purrs and I am satisfied. No, more than satisfied I am very happy. Man, the thought of buying say a new 1200 doesn't even appeal to me because of what I might have to go through. I'm just going to ride. Ummmm next spring that is.

[John in NC]

The spec calls for a gap of around .031, what gap are you guys using with the Autolite platinum?

[Carl U]

Just yesterday installed APP3923 Autolite in my 02 RT. The bike has a Techlusion installed. Gapped the plugs at .035. The bike immediately idled faster and smoother. Rode it around to test for any signs of surge and there was none. Then decided to lean the Techlusion out as an experiment. Was able to drop the cruise adjustment one volt.

 

The bid question is why are these plugs able to solve problems? Anyone have any input? I've tried other plugs and not had this happen. I'm a believer!

[Keeping_It_Real]

I am new to this Autolite 3923 thread. It appears to me that some of you have tried the single or double tip Platinum version of 3929. I called up the guys at NAPA and they seem to express concern that the Platinum plugs required higher voltage? My questions are:

1. Is there big difference between the standard Autolite 3929 and the Platinum plugs?

2. Is there anything else I need to do when I am replacing the spark plug other than the gap setting ?

 

Thanks,

KR

[JamesW]

Just yesterday installed APP3923 Autolite in my 02 RT. The bike has a Techlusion installed. Gapped the plugs at .035. The bike immediately idled faster and smoother. Rode it around to test for any signs of surge and there was none. Then decided to lean the Techlusion out as an experiment. Was able to drop the cruise adjustment one volt.

 

The bid question is why are these plugs able to solve problems? Anyone have any input? I've tried other plugs and not had this happen. I'm a believer!

 

That is a very good question and I wish I knew the answer, why do they work better?? I gap mine at .040" which was about where they were out of the box. Hey, I always thought Ford used Autolite because they maybe owned part of the company but maybe it is because they had a better idea?

[Dick_at_Lake_Tahoe_NV]

How about R1200RT, any problem running this same plug combination in my bike? Maybe if it smooths out the bike it'll keep my left mirror from vibrating soooo much.

 

Primary = Autolite APP 3923

Secondary = Autolite 4162

[Keeping_It_Real]

Let me rephrase my question. When you all installed the Platinum Autolite 3929, did anyone of you do anything special other than just replacing the spark plug ?

 

KR

[JamesW]

I did a precise valve adjust and throttle body sync. Method I used for TB sync was a bit different than just tweaking the right side brass screw and ShovelStroke didn't think it a proper method and maybe it wasn't but it seemed to work well and the folks at Bing Vergasser didn't have a problem with it. Briefly, I removed both brass screws and cleaned them then seated them carefully and backed each one out exactly 3/4 turn. Then I adjusted the throttle stop screws for sync at idle and adjusted cables for sync off idle. I made sure that both throttle stops contacted their respective seats at idle and both cables had slack at idle. I run a Techlusion as well. The frosting on the cake turned out to be Autolite. So, these are the things I did before going to Autolite and if I had it all to do over I would have started with Autolite and maybe saved the bucks I spent on the Techlusion although the Techlusion did smooth things out a bit and did improve acceleration not that an 1150cc machine really needs more snort.

[Dick_at_Lake_Tahoe_NV]

How about R1200RT, any problem running this same plug combination in my bike? Maybe if it smooths out the bike it'll keep my left mirror from vibrating soooo much.

 

Well I just answered my own question and the answer is NO! The thread diameter of the 3923 is larger thann that of the plug in the R1200RT.

 

Primary = Autolite APP 3923

Secondary = Autolite 4162

[Jim Moore]

Let me rephrase my question. When you all installed the Platinum Autolite 3929, did anyone of you do anything special other than just replacing the spark plug ?

 

KR

 

You confused us with the number. It's 3923. Gap it, install it, and ride like the wind!

[Tbuck]

I just installed the 3923 platinum in my 02RT and it runs great. Sweet!

[mrduck]

OK decided to try the autolite plugs in my 04 RT and found out that the 4162 secondary plug is a different size on the outside so the plug socket will not fit them! Tried all the different sockets and none of them will go in far enough! So whatta you guys using to install the plugs?

 

I'm gonna learn to swear in german!

[John in NC]

I had to take a socket to the grinding wheel to make it fit.

Only takes a few minutes.

[realshelby]

People on this forum can be pretty much be divided into two groups. Those with a skepticism for the Autolite plugs and those who have used them. They just plain work, and if your bike surges, they make a very pronounced improvement. I think Bosch probably did a great sales job on the BMW engineers when they talked them into specifying the inferior multi-elctrode plugs.

 

 

I have been following this thread for a while. I just completed a major service on my '04 RT (30K). I had put the recommended and OE NGK plugs in at the 24K service. It ran the same as before which is OK. My RT has always been "cold natured" in that it regularly has to be restarted once to stay running and has been known to stall if you don't keep the revs up a little when taking off.

I bought a set of Autolite 3923's (2) just to replace the Primary plugs. Installed them during the service. It started and stayed running from the first try. It started and stayed running this morning at 54 degrees. During the throttle synch it seemed to idle smoother, and seemed to be noticeably sharper in throttle response while tuning. On the ride to work it ran great. I did not do any full throttle redline shifts so I can not say there is a difference there. What I can say is that it will pull from 3000 rpm in 6th gear much smoother than ever before. It seems to take throttle cleaner when going thru the gears. Of course some will say this is perception from knowing it has the new plugs and tune up. I have done several tune ups on this bike and other than the throttle synch never could tell any difference. Mark me down as thinking the Autolites are better than the factory plugs. I have seen differences over the years in other vehicles when changing brands/style of plugs. There is more to the spark plug than simply starting the fuel to burn. I think different plugs start the burn different and I think multi element plugs may tend to hide the spark from the fuel mixture. Who can say? I will do this to prove my point: This weekend I intend to reinstall the NGK's and let it set overnight to compare starting/cold performance as well as take it for a ride to compare........

[daveinatlanta]

This weekend I intend to reinstall the NGK's and let it set overnight to compare starting/cold performance as well as take it for a ride to compare........

Did you? Results?

[realshelby]

I must admit I have not. I had every intention to. I should as a service to those who may have doubts. I am on my third tank of fuel since the plug change/30K service and so far I cannot tell any improvement in fuel mileage. I can say that it starts and idles better when cold and seems to have sharper throttle response. I will make myself do the change back to the original type spark plugs.

[Laffo IBA#34115]

I just installed the 3923 platinum in my 02RT and it runs great. Sweet!

 

May I ask what gap you used on this plug. The manual I have does not have the dual spark info. FWIW, the snap-on thinwall 11/16 deepwell fits in there.

[Laffo IBA#34115]

OK decided to try the autolite plugs in my 04 RT and found out that the 4162 secondary plug is a different size on the outside so the plug socket will not fit them! Tried all the different sockets and none of them will go in far enough! So whatta you guys using to install the plugs?

 

OOPS grabbed the wrong post. Gap this 4162 secondary plug to what please?

[Linz]

Gap to .35in or 0.80mm

 

Linz

[Dick_at_Lake_Tahoe_NV]

Gap to .35in or 0.80mm

 

Linz

 

I think you mean 0.035 inches for secondary plug gap--and for the primary plug it's 0.040 inches. Also, 0.035inches= 0.89mm

[John in NC]

Where did you get these specs for the gaps?

[BatonRing]

I'm going to try out the 3923s in my '04 RT-P.

 

Is there any consensus on AP3923 (Platinum) versus APP3923 (double platinum)? They are both available at Kragen with a cost difference of just over a buck.. so just wondering what the difference is.

 

Thanks.

TJ

[Dick_at_Lake_Tahoe_NV]

Basically I was just correcting the numbers that Linz put in. However, the Haynes Repair Manual gives the specs for the Spark plug gap as 0.7-0.9mm (0.028-0.035 inches), with a service limit of 1.0mm (about 0.040 inches). Several on this board have recommended 0.040 inches for the Primary plug--and it's already gapped at that as a new plug.

[Bob_Minor]

I'm going to try out the 3923s in my '04 RT-P.

 

Is there any consensus on AP3923 (Platinum) versus APP3923 (double platinum)? They are both available at Kragen with a cost difference of just over a buck.. so just wondering what the difference is.

 

Thanks.

TJ

 

I just use the plain vanilla $1.19 3923's and put in new ones whenever I do a valve adjust. Platinum's that last 60K are great for a sideways V-6 that requires a double jointed midget to change the plugs but I can't see the benefit in an opposed twin.

[knight88]

I have a question, changing to the 3923 would in the worst case scenario do nothing at all, and neither improve or degrade the performance?

[Linz]

I don't believe that I've seen anyone try them and come back here to say that the bike ran worse than before.

 

Mine is noticeably better with the 3923 Platinums. The valve matching did most of the work though...

 

Linz

[BatonRing]

How often do those of you with twin sparks change your secondary plugs? I'm having a hard time finding the Autolite 4162's anywhere.

 

I picked up a pair of 3923 double platinums at Kragen's, and now off to the basement to do the valve adjust and new plugs. Wish me luck...

[davie]

Hi Guys I stay in Scotland but my wife is coming to new york in January for a shopping trip. She is staying in the Hells kitchen area,I am hoping that she will bring me back autolite spark plugs for my BMW1150rt.Is there anywhere locally that she can pick them up? I would be very grateful for your help.

Davie

[Dick_at_Lake_Tahoe_NV]

I'll wish you "Luck", because I bought a pair of 3923 for my '05 R1200RT, and they would not fit as the primary plug. Thread diameter was bigger than the stock primary plug.

[Paul Mihalka]

The Autolite 3923 plugs fit the R1100/1150 "oilheads", but not the R1200 "hexheads".